http://www.1up.com/do/previewPage?cId=3162454

The Flare is one of the more strategic additions to Halo multiplayer,
and can be astoundingly effective when used properly. It only lasts a
few moments, but completely whitens the vision of anyone facing it
when it goes off. There's just enough time to slip into a guarded flag
room or get the drop on a disabled opponent, especially when coupled
with a melee weapon and a good way out. It's especially fun to use
near open ledges, as blinded opponents simply stop moving to assure
they don't plummet to their doom, opening themselves up to all sorts
of destruction. The service tags were still visible in the whiteness
in the version we played, but Bungie is aware of the issue and will
hopefully have it resolved by launch. The Radar Jammer tricks other
players by swarming their radar with fake enemy beacons and peppering
their shields with damage seemingly coming from all sides; it's
disorienting chaos for the victim, and lots of evil fun for the user.