For a standard zoom it has an incredibly good picture quality and an extremely good autofocus. That, incidentally, was also one of the main reasons why I moved to this from 17-55 2.8 IS USM here. There is a clear increase in quality recorded! Not only image quality and Autofukus are very good, L-typical are also feel and better image stabilization (IS va quieter). And the lens looks great :)
For real Weiwinkelaufnahmen I have a ultra wide angle, but feel the large focal length is not as restrictive in the motif quality. Clear, "untenrum" missing something, but what can you thematically compensate well.
I feel especially the telephoto focal length as a great asset, which has very missed you at 17-55. And so I'd rather buy a lens with outstanding qualities and aperture 4, as to have a lens that has aperture 2.8 though, but you could never really use this panel. For me it's definitely better than "plastic bomber" 17-55.
