It can be a good deal. Perhaps an easier commute with higher travel pass to from work. Take bid into a base you will be more senior at thus enjoying more time off and better trips. Bring family with you for the month. Free hotel stay in nice city.
It can be bad. Covering multiple airports in NYC is tough. Yes the company provides the transportation but setting it up each time you commute in is a pain in the rear end. Airport hotels in NYC are not very nice. I asked for a better hotel and it did not happen. In DFW they were more accommodating.
Best one I have done was STL. Great crews. Worst was NYC. First and only miss trip in my career. Knock on wood. Per diem is a minimal reason if you ask me.