Congrats on the lens! I really wanted this lens, but I felt that I wasn't ready for such an expensive lens as I feel I still have time to grow until I could really use that lens, so I had to stop short and ordered a Sigma 18-50mm F/2.8 EX MACRO.
Enjoy the 17-55 IS, honestly I've heard people say the only reason its not an L is because its an EF-S. Post back w/ your shots when you get it