I have the Thunderbolt Display connected to my 13" MBP for more than a year. I'm mostly happy with it, but there are a couple of things I'd really like to see in a newer version (that would even make me consider upgrading):
1) audio out!!! I have this elegant one-cable display docking connection, but to get proper audio out to my high quality speaker system (TB integrated speakers are junk), I have to connect a separate ugly audio cable to my MBP.
2) less reflection!!! Reduction to at least to the levels of the latest iMacs.
3) faster connections (Thunderbolt 2 + USB 3.0).
4) The dimensions and design from front should match 1:1 iMac, so you can use the second screen comfortably beside it.
5) in addition to 27", a 21,5" Thunderbolt Display to match the smaller iMac
6) Magsafe 2, but please also offer an adapter to Magsafe 1 (as far as I know there is only Magsafe 1 to 2 adapter currently).
One more thing "out of the box", that I can't see Apple doing, but would be awesome - add a little door on the back to a space for 3,5" hard drive, which would make the Thunderbolt Display also one awesome and fast Time Capsule! But we all know Apple will just make it thinner...
