My first L-class lens, the Canon 24-105mm L f4.0 IS USM. In short, L-class lenses are Canon's very best lenses. For a while now I have been trying to get lenses for the wide and long end of the spectrum leaving the medium ranges to my now-pretty-much-defunct 50mm prime. I was hoping to stretch and get a real good medium range lens one day. Now it looks like its happening... yay!

This lens is a keeper. I don't think there is something I can think of buying that will replace the utility of this lens. Except maybe if I can ever afford something like the 28-300mm L (which costs 2000+ dollars and would still be clunky to carry around). It was hard deciding between this and the Canon 24-70mm L 2.8 lens, but I eventually decided in favor of the extra range and the IS. My experience with the Canon 70-300 IS USM that I have is that IS is very very handy in low light situations (being a relatively pedestrian photographer, I find myself in low light situations wanting to take pictures rather often, sans a tripod). I can always make up for the aperture by getting a few nice primes, but that can wait.