Thanks everyone. I think I'm going to rent it first. My concern is that it overlaps my 24-105L lens; I know that the lens is at F/4 vs F/2.8. I suppose I could use the 24-105 for outside stuff and the 17-55 for indoor photos only or portraits only.
I don't want to give up the 24-105 as I really like it for landscapes, etc.