The main thing that I see is that you cannot hide junction boxes behind drywall. The box in the ceiling and the ones on the wall would need a blank cover outside of the drywall so that the cover could be removed to inspect/test these splices in the future.
Where wires or pipes run though the top/bottom plate of the framing, the rest of the hole should be sealed with a fireblocking foam/caulk (normally orange in color).
The cables should be secured within 8"-12" of the boxes (limit depends on if the box has an internal clamp or not).
I also see that it looks like he mixed 12/2 and 14/2. I understand that you are not supposed to do this (especially if on a 20A breaker), but I am not a pro.
Did he pull a permit? Will this be inspected?
I'm sure the pros will stop in and iron out what additional issues there may be.