As for the warfare, you're taking command of a mech weighing between 25 and 100 tons (including Light, Medium, Heavy and Assault Mechs) and decked out with tons of your choice of futuristic weaponry, from SRMs (Short Range Missiles) to LRM (Long Range Missiles) and from Small Lasers and Pulse Lasers on up to Gauss Rifles, there's a whole lot of futuristic hurt available at your fingertips. The controls are set up in a simulator fashion, which is to say, your throttle can be set at different speeds and left there, rather than having a more FPS control scheme, where you have to keep holding down the direction key to move forward, but there is also the option of using a controller with an analog throttle and/or stick controls. Also, you have torso rotation, which allows you to easily strafe while running around. This works sort of like a tank's turret, except there are limits because your torso can't turn all the way around.
MechWarrior Online is still in beta testing, so there's a good chance there will be additional match types besides just Assault, but everything I've seen so far is amazing and awesome. And, when it goes live, if you're even slightly interested in checking it out, you have to try it; it's Free-To-Play. There are, of course, things that you can pay for, but many of those things can also be earned with in-game credits awarded for completing missions. The only thing I've seen so far that requires that you pay is to convert mech-specific experience into the more flexible General Experience - and by the time you feel like you need to do that, you would know whether or not you like the game.
Oh, and, yes, I'm currently in the stage of looking around the Internet for some pointers on how to build my simulator. I've seen discussion online indicating that the Steel Battalion controller can be used with MechWarrior Online, with the appropriate drivers and modifications... I'll let you know how that goes.