I've been playing the beta for nearly a week now and overall this game is shaping up to be something really special. Sure there are various bugs in it at the moment, but then it is a beta test so thats the whole point of the thing to iron these out, I personally am a little dubious of the November 2nd release date when they are running a major beta in September but we will see!
Graphically the game is excellent as you would expect from the revered COD series; smoke, explosions, characters and scenery all have a lifelike look to them and framerates are kept high throughout. We have set up rooms with all 12 people (the maximum in the beta) firing and chucking grenades in a small area with no noticable problems in the game engine.
Overall the weapons seem pretty well thought out and portrayed, the only major flaw in the beta seems to be that peoples connections appear to be able to give them a really unfair edge in a straight shootout but hopefully this will be improved before final release.
The perks and powerups system is sublime, really breathes some fresh interest and life into yet another 1st person shooter to have goals to work towards to get yourself better sites on your guns etc etc. You also get 3 special "perk" slots (with plenty of unlckable options) - things like "last stand" where when you are shot (assuming its not an entire clip or in the head!) you fall to the floor and pull your pistol out. There is NOTHING more satisfying than being downed, the guy reloading because he thinks he has killed you while you take aim on his head from the deck and pop him (and maybe his mate if your really lucky!)
You also get powerups in game for killing a certain amount of people without dying - this is the one area of the beta I would say needs some work. You get a UAV for 3 kills, an airstrike for 5, and a helicopter for 7. Whilst it is very satisfying to use these it is not without issues. The main problem is that you can use the UAV, then get another two kills, then use the airstrike (which will normally get you another two kills), so you then have the helicopter which will quite often get you quite a few more. I personally think you should only be able to sue one of these special attacks, ie if you use the UAV it should reset the counter.
This however is only a minor detraction and one which may well be addressed before the final build, I for one can't wait for the retail version and will definately be on this with all the xFUBARx people!