I am not a professional photographer and the only photos I take are of my family or of the vacation we go on. I was frustrated with the quality of photographs taken by my not so shabby Panasonic DMZ, so I plonked some money for Canon T3i.
Spent a month going thru online tutorials and fiddling with the aperture/ shutter settings. I get much better pictures now - in terms of exposure and closer to life rather than washed out or underexposed and blurry pictures.
Yes, i still use auto mode sometimes when I am indoors and in a hurry to capture that moment. And that comes out gorgeous! No comparison with my P&S.
My advise - if you can afford it, and are not bothered by the size of it - go for it! I spent under $600 for a good body and 2 medium lenses, thanks to SD.
Extremely pleased with my purchase so far!