I also have a Thunderbolt display and use it with my rMBP. Previously I used the TB display with a 2011 15-inch MBP. I notice that the rMBP runs cooler and spins the fan at a slower rate - really not noticeable with normal room noise - than the 2011 MBP. I also have a 27-inch iMac and a 13-inch MBP (wife's).
If you don't already have a Thunderbolt then I would wait till a refresh to get the USB 3.0 support and Magsafe 2. Don't think they will refresh it with an up spec'ed screen anytime soon though.
I just did this. My prior setup was 2009 iMac with 20" external display at work - MBA at home. I loooove my MBA.
I'm shocked to say that since switching to my rMBP and TB display I hardly even touch my MBA - really shocked. I can work at home and start out just where I left it without waiting for dropbox sync etc - it's a small thing but really pretty significant. The TB display decision really depends on the accessories - basiclaly with one plug I have my Ethernet, FW Drobo, drives, scanner all plugged in and ready to go.
Video here:
http://www.youtube.com/watch?v=7YRtFaILhhw
The only issue I currently have is I'm getting pretty frequent kernel panics with my rMBP (I don't have chrome installed). I fear that Im going to have to have to send it into the shop to get fixed. About 60% of the time after I wake from sleep I get a Kernel panic and have to reboot - that being said the reboot speed is so frigging fast it really doesn't fell like an issue.
If you don't already have a Thunderbolt then I would wait till a refresh to get the USB 3.0 support and Magsafe 2. Don't think they will refresh it with an up spec'ed screen anytime soon though.
If so, how is it working out for you? I am considering using that combo as an Imac substitute.
2. Amazingly - my TB display came with a Magsafe 2 adapter - nice touch - I wasted $10 getting one first they were thinking ahead.
1. I doubt there will be a TB USB3 refresh anytime soon - USB3 was built into the new Intel Chipset so it was a no brainer move for the rMBP. Since Apple is pushing TB don't hold your breath that they will do this in the TB Display.