There is a rebate on for this lens, as well as a couple of others.
Buy it.
Next to the 50 f1.8 it is the best bargain Canon offers. In fact, it might be a better bargain than the 50 f1.8. It is very sharp, small and light. Downside is it is light and plastic-y. But, I've had one for about three years and never had any problems. I wouldn't do anything stupid with it, but for the price, it is an incredible bargain.