It was very difficult choosing between this and the Canon 10-22mm, the Canon offering obviously slightly bigger range than the Tokina. And Tokina offering F2.8 compared to Canon's F4.0, which is quite a big difference. Both having excellent optics, but with the general consensus seeming to be that Tokina would the winner in optics (if one had to choose). And Tokina also being the slightly cheaper one, but not by much. Oh and the Tokina comes with a lens hood; now this may not seem like much, but a lens hood is pretty much mandatory if you're planning on shooting in daylight with a wide angle lens. So with Canon, you would still have to fork out some extra cash for that despite the higher price.
So really the only thing that was worrying me was the short range on Tokina that have made some people to say that this is actually a prime lens. And I suppose it holds some merit, but even the 6mm range is quite a lot in the short end. Yes, I would had liked to have the 1mm extra to go to 10mm and yes the 17-22mm on the long end was tempting, but in the end, you know what, the 11-16mm seems to be enough.
Now after getting this, I haven't been disappointed. It is rarely I put on my Sigma 18-200mm lens anymore. The difference on the image quality is just too much to bear. The pictures are very sharp and there is very little distortion or vignetting. Sure you might get some on the widest setting, but even that is relatively easy to fix in Lightroom or other such program. And there is no lens on this range that wouldn't have it; Tokina's distortion also apparently is less than that of the Canon (or so I've heard).
It really is perfect for landscape and architecture photography. It's also very good for shooting inside, because of the wide lens and the very high aperture. This allows you to catch much more area in your picture and shoot with much faster shutter speeds. Now it is a wide-angle lens, so there are some challenges in shooting people for example with this. The perspective distortion isn't nowhere near as massive as with fisheyes, but you can't escape it, every wide angle will do that. And that is part of the fun, it does allow you more creative flexibility, especially if you shoot at 11mm. So it will take some practice. At 16mm it is much more forgiving from perspective distortion point of view. Also the F2.8 allows for some interesting depth of field possibilities.
So to summarize, very fast wide-angle lens with quality optics but with somewhat limited range. It seems like a solid lens, with good build quality. And even despite that slight shortcoming of the range, I would highly recommend this to anyone needing a wide-angle lens for their non full-frame sensor DSLR.