I have one of these - and love it. Had it a couple of years now - had one minor problem with the AF motor which caused a bit of a panic but was quickly and efficiently sorted out by Sigma under warranty. My reasons for buying were that I knew I couldn't stretch to the Canon version, I'd heard good reviews of this one, and it fitted in nicely with my game-plan for a kitbag of lenses which would all eventually go over to full frame if I went that way. It feels like a nice solid lens and works a treat with my 40D.