The only things I like about it are that it's slightly bigger and thus easier to hold.
In this picture you can see it very well; the t3i on the left, the t2i on the right.
One thing I really don't like about the rebel series is that they're so small and flimsy. Not nice to hold, and it looks like that with the upgrade it's gonna be much better.
The other thing that's absolutely kick-ass is the built in wireless flash support for multiple flashes. That's so nice.
Other than that I don't really care for anything of the upgrades.
I'd really like a DSLR I can shoot video with and the t2i seems a good option (especially because the price will drop after the t3i's release), it's just that I don't like the size of it, one of the reason's I bought a xxD instead of a rebel.
Oh well, I'm first gonna invest in more glass before upgrading my body.