This isn't the lens that you go pro with, but it's a great learning tool. The fixed focal length means you have to think a good bit more about positioning yourself to take the shot. Also, with the wide aperture you will be able to take natural light photographs and put away that awful pop-up flash. Once you start paying attention to how you compose your shot and what light you have to work with, I assure you will you improve your skills. This is the primary reason this should be your first additional lens for anybody starting out with an SLR (after the kit lens that is).
While this happens to be Canon's cheapest lens, it is also one of their sharpest. It can be a tad soft at f/1.8, but by about f/2.2 it's more than you need. f/4.5 is ideal, but often unnecessary unless you need the additional depth of focus.
That being said, sharpness isn't the only quality of a lens. For just about all other attributes that makes a lens a lens, this piece of glass falters. Focus is noisy and inaccurate, it's built like a cereal box toy, the 5-blade aperture can make for some jumbled background blur, and it seems to soak up crud inside. However, what do you want for the price?
My #1 issue with this lens is the accuracy of the auto-focus. I have a lot of shots that are misses. Part of that is the fact that I tend to get very close to my subject and shoot with a wide aperture for a shallow depth of focus, which is a challenging condition for the lens.