This impression/review is written from a perspective of an AC series nerd who loved PS2 era Ace Combat to death.
My impression of AC7: The game had so much potential and good idea but failed to follow through or push these ideas far enough to hit a home run.

I play AC mainly for the lore, character and presentation, so this will be the main focus of the review. I will not really comment on the gameplay because this write-up is bloated as-is. In this case, I will break up the games in 4 acts: 1. Opening (1-4)  2. Spare (5-10) 3. LRSSG pt1 (11-15)      4. LRSSG pt2 (16-20)

Act 1- PA whispering those delicious strangereal into my ears:
Honestly I thought Act 1 was pretty good. It set up the situation, acted well as a tutorial and maintained player interest. Act 1 really hit the crescendo with Harling's death. GOOD STUFF PA, YOU HAVE ME, I AM NOW INTERESTED! WHAT ELSE WILL YOU DO TO ME~

Act 2- This is (Not) Area 88:
This is where PA drops the ball because the premise is way too cool for its own good.
Like, shoving a bunch of criminals into a million dollar death machine that is loaded with cannon rounds and missiles? YES YES YES. If you think about it, there are so many terrible things they can make the protagonist do to drive home the idea of "Osea being a messed up state" described by Avril.
Here are a couple that I listed just from the top of my head:
1. Run deniable ops like flying in with Erusean paintscheme, commit some war atrocities and pin it on the Erusean government. Which would also work well since their drone war has been squeaky clean in the public's eyes.
2. Erusean military has some research facility that is disguised as a humanitarian supply warehouse/school/hospital or whatever, level that place as an unmarked fighter.
3. Deep strike operation: Dropping laser guided bomb in Erusean leadereship's house that is located inside a densely populated area.
4. Fly into their drone warning network and set off those drones to figure out the weak point. The briefing did say something like "we sent out squadrons to poke around but only 2 planes made it back"

Basically, make players do morally wrong missions to fit in with the theme of penal battalion. This also opens up chance for character development. Which pilot is the mercenary/survivor? Which pilot is thief with a heart of gold ? But instead, the mission we got are arguably not that different from the standard forces with the exception with some prisoner trash talk. Take Long Day, Faceless Soldier and Yinshi valley for examples, really, these missions could probably have been carried out by standard unit and the ramification would be more or less the same.

Act 2's end....instead of going out with a bang, Act 2 more or less ended with a whimper. There is no redemption arc or conclusion on any of the event or character. Band Dog had a lot of potential going for him. He is so ruthless and sketchy, but he was just written off. The game even teased there will be more to come when he agreed Full Band's information would be useful, but opted to kill him later. What was that info? What motivated Band Dog to kill? Why is the game raising this question and just leaving it unanswered?
Why is Trigger's crime instantly forgiven or just glossed over? Considering he MURDERED A HERO (tm) you'd think he wouldn't be off the hook that easily. Instead the HQ kinda goes "eh, you killed enough dudes, lets just stick you into LRSSG."

Cutscenes: I think act 2 had three story cutscene on Erusean's end? The princess arriving, Mihaly's past and the princess watching her own broadcast. All 3 of these cutscenes tried to convey the theme of "Erusea is a nation that has many absorbed territories, and they are NOT happy about it at all". However, it was not immediately apparent. They tried to hint it through Princess' comment on "Erusean has many different culture", "the Sol squadron pilots smiled as they heard the princess' song" and "YET WHAT IS A NATION". But, as a plot point that is so essential for the Erusean civil war in act 4, they should have made it more apparent to the audience.

Side note that will become important later:
"Bulgardarest is in Erusean territory with close ties to Osea" but in the game, they are listed as Osean. I think this is one of the game's early attempt to show that Erusea is full of absorbed territories that is not happy with the current state of affair, but they did not really carry it through. To make the matter worse, they were listed as Osean for in-game communication. This just adds to confusion in the story, which actually becomes a bigger problem in later acts.

Side note 2: Mihaly fight in Yinshi valley is great. Kudos to the sound design team portraying him as an old man trying to push through in a physically stressful dogfight. Bravo PA.

Act 2 started with so much promise and potential, ended up with not hitting the potential while leaving many loose ends and unanswered questions.

Act 3- Long Caster is my Long Long Maaaaaan
I do not know why Act 3 needs new character such as Wiseman and other Strider squadron members. Why can't the game figure out a way to get us flying with Knocker and Clown instead? The main issue is that none of the character really got a chance to develop. What makes ACZ and AC5 work well is that you know your squadmate right off from Mission 1, so there is an ample amount of time for the characters to build up. In the case of AC7, you spend time jumping around squadron and the characters either don't get time to develop, or was outright killed off. The game didn't really use mission 11-14 to build the interaction between player, Count, Wiseman and Huxian either. Missing this opportunity really dampen the impact of Wiseman's death in mission 15, or giving the player a sense of comradery between what remains of LRSSG in Act 4.
Though with that said, I will personally break my rule here and declare mission 11 is one of the best Ace Combat missions in the series yet. The mission rewards risky play (the core inside the facility) that has great pay off (visually, radio praise and point-wise). The open space also invites a lot of creative experimentation with flight path, weapon choice etc. Really, that mission is Ace Combat at its very best. I dont know why there aren't more hard-point/multi-target facility based mission in the game, because that thing is the work of genius.

Misc note 2: Long Caster is best AWACS in AC yet. I think he is the only AWACS other than Crux who I can attribute a descriptive trait other than "well, he's an AWACS". This is how characters should be written, PA. They all need their own memorable quirk.

Act 4: Every frame is so dense that you can't read the radio dialogue
Mission 16 has important dialogue on Belkans, UAVs, root of the war that fill the player in on the key story. However, it was interrupted by the new IFF ID mechanic. When these things are talked about, the player is too busy zooming around and checking target to even digest the information. They could have done this in 1. The quiet moment 2. Mission intro/outro 3. Cutscene. I personally believe that in mid mission, dialogues should really been kept down to action as simple as "PRINCESS TWO TWO TOOK A MISSILE IN THE FACE, SHE IS GOING DOWN" instead of a long winded conversation about drone tech, politics, and MAH BELKAN WITCHCRAFT.  Mission 17 had similar issue, but not to the extent of Mission 16.

Mission 18: Have you seen a mission so beautiful and full of potential that you just want to cry?
This would have been one of the best AC missions/story arc in term of presentation, but it did not live up to its potential. Mission 18, to my understanding, is about an Erusean state trying to break off and get its independence, but that wasn't made fully apparent. This was due to the fact that the cutscene in Act 2 failed to address the fact that Erusea is comprised of absorbed territory. Furthermore, the radio text still states the enemy as Erusean forces, This essentially downplay the narrative that Shilage is a vulnerable historical city is being raided by resource-starved LRSSG.
Sol and Mihaly dogfight involved Sol squadron coming to the conclusion that they need to fight against the UAVs in Lighthouse War. This conversation should have been in a short outro cutscene so its not mixed in a dogfight where the player is too busy killing Mihaly. Since Sol and LRSSG share a comment goal before mission 19.....here is an opportunity that I think they missed that just visually screams Ace Combat:
Sol squadron forms a truce with LRSSG.
LRSSG now lands in Shilage as temporary base.
Shilage air base is a jet hangar converted from castle, with a lot of tapestry and cultural element still around. Sol squadron's spare jets are draped in canvas with Shilage family's coat of arms on it. Before taking off to engage the Arsenal bird, the player gets to speed down a castle tunnel to take-off speed and fly off into the battle.
That kind of imagery just fries my internal ac fanboy circuit, the entire Shilage/Sol vibe is screaming for it. But nope, we blew Mihaly up and moved on... and suddenly Sol squadron just appears in Mission 19.

Mission 19: For most part, that thing is SO AWESOME. Dem keiki kobayashi soundtrack, dem furball, dem bossfight.
Though my bones to pick are still narrative based.
1. Huxian thought Count used some sort of trick/black magic to disable Arsenal Bird's shield.
For the longest time, I was wondering what is up with that... but I think what probably happens was, Count had a civilian radio taped on in his cockpit as he previously mentioned. This is why he could hear the princess destroying the elevator monitor device. I understand this is probably PA trying to play up the idea of Count used to be a fraud... but given the player is aware of what the princess is up to, at the surface level, Count's action and Huxian's reaction just felt bizzare and misplaced.
2. I do not know why PA wants to have a cutscene involving the princess getting blown up, only to have her made it out alive in mission 20...Especially with the flashback in the intro of Mission 20, it looked like the princess died and there is something to do with drone. But all of that had nothing to do with the story....I do not know what point PA is trying to make, this is still confusing to me.
3. Avril's character got shafted majorly on the Anderson Carrier. For a character who is built up to be highly competent with aircrafts, and was given the scenario of "we dont have any flyable plane" and the intro of "I will build a plane that flies, you can count on it". You'd think "this is it, this is the time for Avril Mead to shine" But PA ended up throwing it all out by having LRSSG find the carrier is full of brand new jets, and in the end Avril pretty much did.....nothing except REALLY BUFFING UP THAT CANOPY SO THE PLAYER CAN SEE THAT DARK BLUE.
My suggestion for this? You have two things that could have been done without overblowing the development budget.
1. Avril's handy work allows her to convert any non-carrier compatible jet into steam-catapult capable.
2. Avril gives your plane a one time super tune-up that is good for the final battle (Think of this as super gravity gun in HL2 ending or the Pilot survival kit in the end of Titanfall 2)
Both of these will drive home the idea that Avril is competent at her job and ties the narrative into the gameplay.

These are my main impression that I had after playing AC7.
At this point you all probably think I want AC7 to fail, but the truth is I wanted this series to succeed very badly and I wish it could surpass even the highest of my expectations. This is more of my attempt to analyze area where AC7 fell short, and what in theory, could improve the game's narrative experience. I thank you all for reading it, and please feel free to add to my point or argue against it. This is what discussion is for, after all.