My thoughts, prepare for a long post:
Okay so these are my initial thoughts after playing 1-2 hours of it yesterday. This is just for those of you that are wondering about it, but can't get your hands on the Beta. Of course these are merely thoughts on the Multiplayer and keep in mind this is a Beta.
So the first thing I notice is how unpolished it looks compared to COD4. The graphics look very downgraded. Possibly due to it being a Beta. I have no idea. This is not much of a problem as it is not very noticeable.
The other thing I realized is that it is very different in terms of shooting. This is a WWII game and not based on modern warfare, which we are ever so used to. Many of the effective guns are bolt-action or semi-automatic guns. This changes things quite a bit. Instead of running and blasting like a mad man. You will certainly need to be more cautious. And it is apparent that people are "camping" more.
Even though this is a game based on WWII, it still contains many different forms of perks and equipment that remind me of COD4 quite a bit. (Ex. Satchel charges = C4 explosives, Pack of Dogs = Helicopter) Which by the way is very difficult to kill. I find that dogs are more effective than Helicopters.

So the similarities and charm is clearly there, but in a new coat of paint. Which in my 2 hours of playing seems like a breath of fresh air.
The guns are as expected. You have the usual: Thompson, Trench Gun, Springfield etc. Some seem to be very underpowered especially some of the single shot rifles. Perhaps it needs some getting use to. I haven't got a chance to try any of the later guns as I have not unlocked them yet.
Then there are new additions to the experience. Tanks. Tanks are mainly for larger maps that have more of an open space. You will find that tanks are generally overpowered. You will find yourself getting raped by a large explosion as soon as you see a tank. Although many may disagree with me, I think that tanks can easily be taken out at the same time. I think they did a good job of balancing this out.
Maps. Maps are a bit different from COD4 maps. Like I mentioned before; things like Tanks allow for more of a variety of size when we're talking about maps. For me, some maps seem a little awkward and unbalanced. Many maps are built upon a circle type of walkway. You will find yourself walking over the same patch of land you did before. (Mainly in TDM.) I would imagine this would get tiresome quick, but who knows? We'll have to wait and see.
So yeah, it was pretty good. I enjoyed it quite a lot. For those of you looking for a brand new Call of Duty with new features and revolutionary gameplay, wait a few more years. For those of you that have not played COD very much, this looks like a great time to check out the series. And for the COD4 players, you might want to check this out if you're getting tired of the whole modern thing.
Of course these are my views, and strictly from the Beta.