I don't know why people are complaining about the graphics, I think they are great. Everything is buttery-smooth with lots of details in the environment. I think they may do something similar to what happened in Ghost Recon, where the developer simplified the graphics a bit in the multiplayer to make it run better. Halo is the only game series where I completely forget about the graphics and just enjoy playing the game, so I will be very happy if the end result is atleast how this beta looks.
I was only able to play one game before I left for work, but in that one game I wa hooked. It felt familar enough that I could pick it right up, but different enough to be exciting and new. I like all the new grenades, I don't feel like they can be thrown as far as in Halo 2, that was something I will have to get used to. Also, reloading took me a minute as I am used to X being reload.