After two weeks of regular use, I can say that I'm very happy with it. It's good. I haven't strapped anything on since receiving it (yet) - it has a very useful range.
I was a bit apprehensive prior to buying the lens - and that is only because I read up on the lens. I even rented and borrowed prior to buying and can't fault any of them. I should have started with this lens instead of going the circuitous route of 28-75, Sigma 24-70 and finally the Canon 24-70 - and saved myself the time and tears.
Weight? I ain't complaining - image quality is everything. You don't buy a Ferarri for the comfortable seats...