As the previous poster pointed out, big lens. Borrowed from a friend for a day. Got great shots but it was too big for me to carry around.
I thought the build quality was better than Canon L, I have the 17-40 and wife has 70-200, and this seems better build. Also like the fact that it was black. Come on Canon enough with the UGLY white lenses.
Image wise though, and that is what counts, this lens will deliver.