Pros: Item arrived fairly quickly.  Placed order on Saturday, item arrived on Thursday.  Item was in new condition still in packaging. (Note, the item I purchased was shipped from a US address.  Since I have placed my order this seller has started selling the item for $2 cheaper, but shipping from China.)

Cons: Item was described as being for Macs.  It also is purposely designed to look exactly like the official Mac adapter, thus trying to confuse buyers into thinking it is the actual official adapter.  There are several differences between this and the official Mac adapter.
The disc included with the item is practically useless.  It is an 8cm disc that cannot be read by slot loading drives.  This means every mac product that is sold today cannot read this disc.  Nevermind the fact that most people looking to purchase this device are probably macbook air owners and don't even have a disc drive in the first place.  I was lucky enough to have access to a tray loading usb disc drive, so I managed to get the disc files loaded to my macbook air with it.  The disc contains 8 folders, seemingly randomly named, and a readme file.  The readme file absolutely no information that is valuable to the end user.  It looks like it is instructions for the people that created the disc itself.  The folders on the disc appear to be various drivers for other adapters and items that the seller sells.  It appears that in order to save time drivers for all the products are put on the same disc together.  But since none of the products are clearly named (How am I supposed to know that the chipset inside this piece of plastic you sold me is a MSC7830?) it is a guessing game as to what driver works with the device I just purchased.  Eventually I managed to guess correctly, and the driver installed.  After a reboot the adapter seems to be working properly.  It seems to be a bit slow, much slower than the built in wireless adapter, but it does work.  The unit also feels like cheap plastic and has an annoying red light inside the plastic casing that blinks when the device is in use.  Something tells me the official Apple adapter doesn't do that.  I suppose for $12 I can't complain too much, especially for something I'm going to throw in my laptop bag for "just-in-case" scenarios but even considering that, if I had to do it all over again, I would have sucked it up, spend the extra $10 and bought an official Apple adapter.

Bottom line - Buyer beware.  You get what you pay for, and in this case, I didn't pay too much.

I'm not leaving negative feedback because at the end of the day, I have an adapter that arrived in an acceptable amount of time and works as it's supposed to, but there surely wasn't too many other good things I can say about this transaction.