I used to own one of these -- and I really miss it. It is simple, inconspicuous, and extremely fast. The fact that it opens up to f/1.4 (and produces great bokeh, I might add) should be enough.

This should be the first lens you buy for your Canon digital SLR. It is absolutely the best bang for the buck in terms of image quality, durability, and versatility. Don't be tempted by the 50mm f/1.8. It is less expensive but the build quality is terrible.