I have used it, though only with halo (1) with a friend in the next town. It was very laggy (as to be expected when you cram 10mdbit through 384/384). I have not tried it with Halo 2, although I would expect the lag with that to be no worse than with XBox Live, since halo2 is designed for internet bandwidth and there is no reason ofr them to use a drastically different scheme for LAN than they use for Live.