I spent about 5 hours dogfighting online last night with the XBOX, connection was great, no lag - just a lot of bullets ripping holes in my wings! There does seem to be some problems with "starting" a room though. I suggest starting a room and then sending invites to people, this seemed to be the best way to get a dogfight going, otherwise you get the "servers down message".
But once flying the the multiplayer experience is truly exhilarating...but be warned...there seem to be some pretty decent pilots out there already, and the won't hesitate to blow your wings off...
See you in the skys...first I hope...
