Can connect up to 8 players either lan or via internet. Host has full control of all arena variables from terrain to ammo multi.
Best of all its free, you don't need a paying AH account to fly the H2H. So its a great way to introduce a friend to AH and get him hooked.
The Only thing that H2H doesn't have is a way to save your arena settings. Would would IMO be a cool addition.