Slashdot has several reviews of the private preview of the Halo 3 beta.
http://games.slashdot.org/games/07/05/12/1655205.shtml
Here is part of one
As expected, the Halo 3 Beta kicks all varieties of ass. Halo vets will appreciate the refined weapon balancing, added Equipment strategies and intricate new levels to explore, while series newcomers (if there are any) will have a blast messing around with items that are just silly fun to use, like the Bubble Shield, Mancannons, and Spike Grenades.
It's unmistakably Halo gameplay, despite the rearranged controls (which feel natural after 10 minutes), and all of the additions fit perfectly into the multiplayer universe we've come to love. The interface has been overhauled and is even easier to use, and you now have such niceties as being able to change your control layout at any point on any screen.
While the visuals are rich and beautiful, it's the audio that's really impressed us so far. The rumbling throttle of unleashing dual SMGs makes them feel incredibly powerful, and the Spartan Laser tearing past your head is as scary as you'd imagine. Audio cues are more important than ever, and the better your sound system the more next-gen this will feel.
Perhaps best of all, the weapon layouts and increased combat options bode well for the balance and pacing of matches far after the game comes out. We finally got a few matches in on Valhalla, and between the added modes of transport, varied terrain and huge variety of weapons, every second feels unique and dynamic. A single Bubble Shield can completely turn the tide of a lopsided battle, and you rarely feel completely down and out. Trumpeted visual touches in Valhalla, like grass and water, really make it feel verdant and alive, and it holds the crowd well as the successor to Blood Gulch and Coagulation.
http://www.1up.com/do/previewPage?cId=3159450
