James,
I shoot it primarily on a 30D and out of the studio, it's fine as a portrait lens and pretty good for just about anything else. In a studio or somebody's home, I think you have to go with a zoom that gives you something wider. I usually use a 17-40L or the 28-135IS.

Having recently gotten the 85mm F1.8, however, I don't really think of the 50 as being too long. In 35mm days, it would be the ideal focal length on a crop body like the 20D/30D.

But beyond the IQ, which is very high, what I love is the size and weight. It makes for one remarkably light travel camera/lens combo if you don't mind not having the flexibility of a zoom. I'll use it with extension tubes for macro and with a Kenko 1.5X Telextender for medium telephoto (yes it actually will auto focus with that extender) and sometimes with both for major macro.

It's a nice, fun little lens that takes you back to the good old days when a 50 was perfectly acceptable for almost anything you needed to shoot.

Jim