Kudos to mad.max, who (with much sweat and blood) tracked down and transcribed portions of the Halo preview in PCGamer UK that we less fortunate North Americans might have a peek at it. A few highlights provided for us from the article:

The sheer weatlh of subtle touches they've managed to cram into the game, including individual animations for pistol magazines, spent cartridges and the movement of characters while inside vehicles, suggest that this may be the first shooter with more to it than simply gibbing more aliens than the next guy.

And in the summary at the end of the article, this quick rundown:

What's in it for you : non-linear missions together with team-based gameplay for both single- and multi-player games. Vehicles, two playable races, some of the finest animation you've ever seen , and shed-loads of weaponry. A potential Half-Life beater.

A potential Half-Life beater? Given that Half-Life is considered by many to be the best FPS of all time, this is high praise for a game so early in development.