This is a good move for them. I live in Philly and thought they got lucky last year. Had they played in the AL East, they probably would've finished in 4th place and not even made the playoffs. Similarly, had the Sox been healthy last year, they would have beaten the Rays and probably swept the Phils. The way the AL East manhandled the NL East this year pretty much proves that.
I think this move, however, makes the Phils legit contenders, even against a healthy AL powerhouse.
Lee is overrated, but he's going to be even better in the NL.