I actually just went to look at them this weekend at my Cingular store.
I looked at the Razr and talked to my buddy at the store, and it's a really sharp looking phone. My friend actually said that the MPx220 is a better phone however. He didn't go into specific details but said its an all around better phone, and its also $300 compared to $500.
The Razr's major draw is its tiny... that's pretty much it. It's VERY tiny, and if you want the hippest thing around, I guess that might be it. For me though, it was actually a bit TOO small for my liking, and I prefered the MPx220 by a longshot.
If it were me, I'd get the MPx220... its got everything the Razr has, and beats it in a lot of places. Higher quality camera, does video recording I believe, etc etc.