Well my Tamron 28-75 was a bit buggy...at 28mm the AF was terribly slow, like something was causing it to crunch. If bumped to 32-35mm, it was usable AF, but not as fast as I'd like. In addition, something else was weird with the 28mm end... my flash zoomed in to 50mm while the lens was at 28mm. The lens only accurately told the flash what MM it was when between 35mm and 75mm...sort of weird. As everybody mentioned, (BigMike stresses this over and over, and TWICE now I have regretted not listening to him!) 28mm is not wide enough for a crop camera. I yet again find myself going to my slower Canon 17-85 f/4-5.6 IS lens due to AF speed and the wide end. Well, I just called B&H and got an answer right away. They are going to give a full refund, as well as give a prepaid shipping label. B&H ROCKS! Now, I am in a different phase... instead of getting as much crap as I can, I am focusing on selling things I don't use, and hopefully buying a couple of nice things. I realized that I can recover about $800 from things I don't use at all, and then put that towards a lens upgrade. I'll probably end up with the 17-55 f/2.8 IS (replacing my Canon 17-85 f/4-5.6 IS) and the 70-200 f/2.8L IS (replacing my Sigma 70-200 f/2.8). I just ordered the Canon 50mm f/1.4 to replace my 50mm f/1.8, and can't wait to get it in. AF speed is SO important to me, because of the type of things I shoot, and who I sell the photos to. The 17-85IS has spoiled me because of its USM. In dark situations, or fast action situations (MMA matches or auto races) I can mash the button, and it will focus so fast I don't have to wait for it. Sigma's HSM is just a hair slower, which makes a big difference. Not to mention Tamron's complete lack of xSM is slow enough to keep the lens in my bag during sporting events.