Not a bad lens at all. If you can get the USM one it is a little better. The other comments about being very long when zooming to 300mm and poor light response is true - it is a budget lens, so you'd expect no different.

It may be worth looking at one of the newish Sigma lenses -

http://www.sigmaphoto.com/lenses/lenses_all_details.asp?id=3304&navigator=3