I found The Thief a rather enjoyable read. I quite liked the main character, Gen, despite his tendency to be whiny. Little things that would bother me in other books didn't bother me so much in this one, though I would have liked very much to have seen some more character development around the magus and the others in the group. The nice little twist at the end was unexpected for me...sneaky Gen.
I liked the world that Megan Whalen Turner has created, especially the tales of creation. The stories told by Gen and the magus throughout the novel made the world more real and complex by adding a touch of history and introducing us to the gods. I quite liked that little touch.
Can't wait to start on the next one. I've heard it's much better!