So this is in open beta at the moment. Onlly has EU and RU servers, but, I've been playing and doing fine from the middle of the US.
Very similar to the World of Tanks model, only with WWII and some early Korean war planes.http://warthunder.com/
I'm having a blast playing right now. Only rank 5 in the US and 3 in the RU tree, lots of fun so far.http://www.youtube.com/playlist?list=PLSPT1I-KtyUF0iv6Emae0NSZlbkJxsKik
Spent a lot of time watching game videos here.
The game has SP missions (that can be played co-op with 3 others as well), 2 campaigns (have to buy them, come with some nice bonuses), mission editor, and a dynamic campaign (co-op'able). All the money/xp you earn doing these is carried over to the regular mp as well.
There are 3 levels of realism for matches. The arcade level is great for just jumping in and having fun. You can use a joystick, however the mouse and keyboard controls are well done.
Eventually they are going to have players manning tanks/vehicles and naval vessels as well in the same missions. Kind of reminds me of the old flight sim that I played on AOL (think it was on Genie as well) in that respect. You could capture bases on the ground, man AA, or fly around and shoot things up.