Although it's about 0.6-inch deeper, the T2i's body weighs the same 18.6 ounces and looks extremely similar to the T1i.
The little things
It may seem minor, but Canon hasn't switched to the cheapie thin plastic body and lens back caps for its entry-level dSLRs the way Sony and Pentax have.
The T2i has a very comfortable grip, textured and rubberized in all the places your fingers touch and workable for single-handed shooting.
The T2i's control layout is almost identical to the T1i's; however, Canon has redesigned many of the buttons--they're flatter, and a tad harder to feel. Now there's a dedicated button for jumping into the Quick Control panel. Other than that, the control layout is the same as it's been for many generations, and the layout pretty much works. However, I'd really rather have the ISO button in place of the Picture Styles rather than it being on top of the camera--that's where most point-and-shoot upgraders would expect it to be, and would consolidate all the shooting controls in one spot.
Canon did move the button that doubles as movie record and Live View enable, since the Q button took up residence in its old spot.
I'll make the same complaints I brought up with the T1i: no custom settings and poor placement of the movie mode. The latter is really cumbersome, in part because the dial doesn't spin 360 degrees, so jumping between movies and still shooting modes is really annoying.