I actually just got my MacBook back today from getting the top case changed.
It's an entire assembly. That is: palmrest, button, trackpad, keyboard.
The bezel around the screen did not get replaced. There's a bit of discoloration (very minor, can hardly tell) up by my iSight is the only way I know, so that did not get replaced. Which, I'm fine by.
I'm quite happy. I took my MacBook in last night (about 5 pm on a Friday) and they called me this morning (11 am on a Saturday) notifying me that it was ready for pickup.
About a 250 dollar repair, for free. It looks like it's new again.
Definitely take your MacBook in if it shows discoloration. You won't be disapointed.
It feels about the same to me, a bit smoother, maybe.
I've got a MacPad (
http://www.macstyles.com) coming to me in the mail, which I was gonna put over my old discolored palmrests. I haven't decided if I'm going to put it on or not now.