Often overlooked gem
This lens is often overlooked and neglected in favor of the famous Tokina 11-16/2.8 or this lens' predecessor: the Sigma 10-20mm. However, it offers excellent sharpness from my experience, and it's as wide as it gets when it comes to the APS-C format while staying rectilinear. Take care when shooting with this lens, or you'll photograph your own feet if tilting it just slightly downwards.
As for the speed, it's not as fast as the popular Tokina lens, but remember that the old "1/<equivalent 35mm focal length> seconds" rule still applies for steady shots. That implies that you'll hand-hold and still get pretty good shots even at 1/15 second shutter speeds, which is pretty crazy and has definitely reduced the "need" for f/2.8 speed for me.
5 stars for optics from me, but reduced by a star part for imperfect speed, and part for not being able to use a filter on it. Still, not lower than this, since this is a unique lens in the APS-C lens landscape.