It's not just the bowing... the brushing is bad, the control joints don't look good, there are chips and rough spots, and that's just what I can see in the pics. Totally unacceptable and in no way are any of those things normal. There's no fixing all that. I just wrote this in another's thread: it's not wood! You don't get close and then go back and cut and grind and sand and reshape, whatever. Concrete is supposed to look the way it's supposed to look just before it sets up. You don't go back and "adjust it" after that. Who was responsible for locating the spa cut out? Also unacceptable. Reject the work. Don't pay him. It's a redo.
So sorry that happened to you.