Nothing is wrong with it. Probably just a little "the grass is always greener" syndrome. I like the size of it. It is a little on the light side; doesn't feel flimsy, but not built like a tank.
Someone locally has an old Nikon 24mm 2.8 that has me curious, but the Sigma has that covered...
I guess I should be looking at the Tokina 11-16 and something over 50mm to cover my bases.