It's a fantastic port, very well done. Performance is nice, there is stuttering yes, but I think that is due to the levels being stream loaded (there are very few load screens, and they are very short). All the stuttering I've encountered happened in empty areas, never during fights, so that's why I think it's due to the game loading in the background. Basically, it feels like it was built from the ground up for PC.
There's been a big stink about the Windows Live stuff, and I wasn't too happy about it when I first heard of it. But in practice, it's no big deal, it's basically like having Steam's friends list. You can do just about anything with a free Silver account; host a match, join a match, whatever. The only thing you can't do is join RANKED multiplayer matches, that requires the paid Gold subscription.
I must say the Versus multiplayer is very very fun, I thought 4v4 matches would be either too fast or too boring, but the balance of the maps, player health, and weapons make it perfect. Also, voice chat is built in and runs automatically, just talk into your mic and that's it. I also love the third person perspective, looks great and feels very different in a good way.