This is the lens I recommend to everyone who starts with crop and wants to get their first nice lens after the kit lens. Had two copies, and loved them, but got rid of all my crop stuff.
Incidentally the full-frame "equivalent" of this - in the eyes of Sigma - is the 24-35 f/2, which is actually an under-rated lens. People hate the short zoom range, but combined with a 14mm f/1.8 and a 50mm 1.4, it's a potent threesome.