It's a bargain of a lens, well worth playing with and a good introduction to wider aperture, low light, shallow depth of field, fixed focal length (prime) shooting. The focus isn't overly fast and can sometimes miss but then you can't expect perfection, also it's not brilliantly sharp at f1.8, however I've used one quite a bit, even on my 5DmkII (for fun) and it does fine. I now have progressed to the Sigma 50mm f1.4 for a bit more sharpness and better AF (oh and 2/3 stops more light).
You will certainly have fun!