Yeah, not being able to use my Lee filters weighs heavily against this lens for me. That, and the flare susceptibility - that looks ugly! If I didn't have the Samyang 14mm, the excellent coma on the lens would be a major plus when weighing things up. I think an upgrade of my 17-40 will be my next lens. At the moment, Canon's 16-35 f/4 is looking like the best option, for me. It will be interesting to see what Sigma bring to the party...