It's awesome! Of the three PC formats (Vive, Rift, and Windows Mixed Reality), Vive is definitely the premium option. It costs the most, but it also performs the best.
It isn't perfect though. There is a build quality problem with the touch pads of the Vive controllers which results in them not clicking in certain directions after some time for most people. When that happens you can either try to get HTC to repair or replace them, which will involve sending the controller away and being without it for a couple of weeks at least, or breaking the warranty and opening it up to fix it yourself.
I chose to fix mine myself with the help of a photo guide online, it involved using a Torx 5 screwdriver and a normal phillips head screwdriver to take it the controller apart and then re-seat a tiny rubber disc on the under side of the touch pad so that it hits the micro switch correctly again.
When mine first went bad after a few months of use I repaired both of them twice over the course of a couple of weeks (I guess I didn't get it right the first time),
After that they lasted for another good number of months until I finally had to re-do one of them again last week.
I think the second repair on one of them I replaced the rubber disc with a little circle of cardboard instead and that one has stayed good since then. Repairing the other one last week I did the same and it's good again now, and hopefully will stay good until the Knuckles or some other Vive compatible controller gets released.

The Rift is a fair bit cheaper than the Vive and from what I've heard from friends who have had both, the difference in tracking quality on a 3-camera setup is almost trivial. They have some issues with certain configurations of USB ports, so buying a dedicated USB expansion card for them is advised. Their controllers are widely praised as being the best around right now. Lighter and more comfortable to hold than the Vive's and less likely to damage things if you hit walls or TVs with them (Which is a pretty common thing).
You'll need a good supply of AA batteries, or some nice sets of rechargeables  since they don't have built in USB charged ones like the Vive.

WMR is the budget option. Cheaper again than a Rift, but with some pretty heavy drawbacks to go with it. There are a number of different WMR units available from different manufacturers, but they all suffer from most of the same problems. They track the controllers via cameras built into the front of the headset, and the headset itself uses internal sensors to track its rotation and position in space. The plus side of that is that you don't have to set up any external boxes like the Vive light houses or Rift cameras, making it very portable especially if you're running it from a laptop, but the tracking suffers for it.
From what I've heard the headset tracks pretty well, doesn't drift much, but the controllers are the real problem. The cameras on the headset can only really see the controllers when you're holding them in front of you. As soon as you move them out of your field of view it loses sight of them too. They've got some built in gyro and accel sensors to fall back on, but I've seen people playing with WMR and their hands are very unreliable when they aren't directly looking at them.
WMR is probably fine for a seated setup, but for proper room-scale experiences I wouldn't recommend it.

When looking at buying a Vive you've got the choice these days of the standard Vive headset or the Vive Pro headset.
I haven't tried a Vive Pro, so I've got no first hand knowledge of the difference, but it's said to have a higher resolution display which may result in clearer images.
I've become very used to the resolution of my Vive, so it generally doesn't bother me, but if I look for it, I can definitely see room for improvement in it. Things generally look pretty good up close, but you can notice the low res issues with things more distant, and especially when trying to read smaller text.

In terms of VR in general, it had changed my gaming life. It's rare now that I play a game that isn't in VR. The immersion is just a whole other level. I play a lot of Rec Room which is a free social/sports game basically like Wii Sports in VR, but with much more content including paintball, laser tag, battle royale, and co-op dungeon running quest modes.
The other big draw on my VR play time is Minecraft. I use a mod called Vivecraft which brings VR support to the Java version of Minecraft. I've got a good group of friends that I met through Rec Room who I now play a lot of VR Minecraft with. It works for Minecraft versions 1.7.10, 1.10.2, 1.11.2, and 1.12.2, and is compatible with Forge and most Forge based mods, so the possibilities are pretty huge there. It's also going to get 1.13 support some time after 1.13 comes out.
It also allows cross-play with non-VR players on Java Minecraft.

The Windows 10 version of Minecraft comes with VR support for Rift and WMR, but not Vive.
By all reports it's nowhere near as good as Vivecraft though, which supports all three standards.

So those two multiplayer games are where about 90% of my play time goes these days.
I've also enjoyed some of the classic games that have been ported to VR. Skyrim, Fallout 4, Serious Sam.

Rhythm games are another pretty popular genre for VR. The stand-out example right now being Beat Saber. It's basically DDR with lightsabers. You've got a red one in one hand and a blue on in the other hand, and you have to slash through cubes that come at you using the correct saber and in the correct direction as marked on the cube.

There are a number of other VR games I could describe and recommend, but that's probably enough for now, eh?