Newly framed bathroom wall not square, how bad will the tile look?
That looks like nearly 3/4 inch in a 2 foot run. That is a lot of angle, and I think most carpenters would consider it unacceptable on a new framing job (unless there were some underlying issue, like a pipe or an old beam preventing a square outcome). 

But it also sounds like your contractor is challenged when it comes to getting something square. You can try again, but you may still be disappointed.

An alternative is to use a brick pattern on the floor.



The lack of a straight line on the left would make the angle cuts less noticeable.