Bought an XT in 2004, and XTi in 2006, and now the T2i in 2010. Wasn't sure that I really wanted to upgrade. I mean, what's really the difference between 10MP and 18MP, right? And who cares that it shoots video?!? Seemed kind of gimmicky, and I already have a standard resolution video camera using miniDV tapes, also bought in 2006. I figured it would be just dropping ca. $900 to say I had the latest tech.
Well, I was WRONG! The T2i is outstanding and awe-inspiring. The upgrade from the XTi is well worth it. I really can't say enough good things about the image and video quality. You really just have to see it to believe it. And I don't feel the need anymore to offload the pics to get a good view of them since the LCD is so big and bright. I don't mind storing them on the camera until needed for other purposes, carrying it around and showing off my beautiful pics and videos to everyone. Two 16GB SDHC cards are plenty of storage.
I really like the new 63-zone metering system inherited from the 7D. It's really hard to take a poorly exposed shot anymore, but I'll keep trying because it's so much fun! Autofocus works fantastic, too. Of course, composing a shot is and has always been up to the photographer. Don't look to any camera to do that for you.
Before buying, I saw some negative reviews regarding build/size and video. Let me just say that, although I've never used a metal-bodied camera like the 7D, I have nothing to complain about regarding the build or the size of the T2i. The camera is plenty rugged enough outside of taking it on a safari or through the everglades (although I don't why it wouldn't withstand that with enough protection), and it's plenty big enough even for my largish man-hands. I do have a battery grip on order, more for having two batteries on-board with extended battery life than for the size bonus.
Finally, regarding the video: good-bye old video camera. I've seen reviews questioning why you'd want to have video capability in your SLR, whether you'd really use it, and how ineffective they are because you have to accessorize them so heavily to get quality results. All of these evaluations are irrelevant to a NON-PROFESSIONAL film-maker. The T2i is a perfectly exceptional and convenient replacement for any dedicated video camera, and the video quality is superb--better than my dad's new dedicated SONY HD handi-cam that cost approximately the same as my T2i. It is perfect for family & vacation movies and anything else the non-professional would do with it. And, as has been shown by the number of professionals adopting them, DSLRs are quite capable even for professionals with the proper outfit.
I will also say that focusing with video isn't the bear that I've read about or expected. The camera will autofocus for you both before you press the RECORD button, as well as during the filming, if you so desire. Some might say it's slow, but it's no slower than any of the handi-cams I've ever used. Again, this is something that is only relevant to a professional user. There's always manual focusing, too, which isn't hard--no loupe needed. Of course I grew up with a manual-focused 35mm camera. We didn't have autofocus back then (that anyone could afford or that worked worth a damn), and ETTL had just come into wide-spread useage.
I really can't say enough good things about this T2i. I don't regret the purchase at all. It's a very worthy upgrade, certainly from any point-and-shoot, definitely from XTi/XS/XSi, and probably also from the T1i. Very enjoyable camera that makes you run around taking pictures of EVERYTHING once again. That alone is worth the money!