I got the body to serve as a lightweight carry-along tool when backpacking, cycling etc, when I don't want the extra bulk of 5D (which I also own). I was surprised by the good image quality, and the weight is certainly a plus when bicycling (I usually have a Sigma 18-125mm lens attached, which is light as well), I most certainly notice the difference compared with 5D / 28-135 IS which is my preferred combo when I can afford the weight.
Body is also small, and my hands aren't... no room for all my fingers, but I can live with that, after all I wanted a small cam!
A pleasant surprise was that my 100-1400 IS lens, with Canon 1.4 TC, is able to autofocus (albeit slow - hunts and takes seconds...)! 5D won't AF at all, so I think this combo will also be useful when shooting birds and other nature stuff... and yes, I'm using the tape trick with the TC.