As far as photography and video go, it's not all that good, but if that's what you can afford, it will certainly get the job done for stop motion. I'm pretty sure I came across a semi-professional stop motion film shot on it once. It will give you the image quality improvement over other cameras that you would expect from a DSLR, and the advantage of full manual settings (although with any camera in the Rebel series you have to deal with custom white balance). The only concern that I would have is that it's not meant to be a camera to beat up on, like the more rugged cameras higher up in the line. It's meant to be a family camera for taking pictures of the kids on vacation, so if you're going to be really intense on it and shoot some long films properly where you actually take a picture for every frame and don't repeat frames, I'd worry just a little about it's life span. However if your not planing on shooting 10 minute films in this fashion (I don't, I tend to repeat some frames in the gaps between movements, and no one can tell the difference) it shouldn't be a problem. I've never used the 1100D, but from what I can tell from the specs it should be perfectly fine. 
Oh, and if you buy one, just get the black, the colors are just silly and hard to take seriously. 