I recently bought one from the apple store and i have to say; It's showing it's age.
It requires an adapter for the new power cables (included) which is annoying.
It lacks USB 3.0
The resolution on my 15" rMBP is higher and if the iMac rumours are true, the next thunderbolt display will be pushing 6k resolution.
Although gorgeous, It's quite bulky and thick looking.
It's really heavy.
The built in speakers are not very good
The built in microphone is god awful. People tell me I sound like i'm in a tunnel.
It's not worth the money right now. Wait it out.
I bought an Apple refurbished TBD recently for about US$550 and thought I'd provide another perspective.
So far I have been really pleased with the TBD. Sure, the resolution is not as high as my 15" 2012 rMBP, but I sit farther away from it than I do my rMBP so it isn't really that noticeable to me.
The power adapter is, to me, a non-issue. It's not like I'm taking the adapter with me all the time.
The lack of USB 3.0 is disappointing, especially if you require fast transfer speeds. I have been using USB 2.0 hubs for a while though with my rMBP and I don't need fast transfer speeds for anything, so it's fine for me.
It's thicker and heavier than the 23" LG it replaced, but it's not ridiculously thick or heavy and I think it still looks quiet nice. I'm actually saving a lot of desk space with it because I got rid of some USB hubs I was using and my bluetooth speakers.
I've found the built in speakers to actually be very good, and much better than my bluetooth speakers. Granted, I live in a small studio apartment in Tokyo so I'm not really blasting music that much, but I've found they are perfectly fine for my use.
I've had no issues with the microphone or anyone say anything to me about it sounding bad.
I don't think it's worth $799 and the US store seems to have them overpriced. In the Japanese Apple store a refurbished TBD is about US$640 at current exchange rates, and some third-party retailers have official Apple refurbished displays for even less. If you can find a deal on it like I was able to, I think it can still be a great monitor. Otherwise, I'd get something else or wait to see if Apple eventually releases an update.