If you love the genre, you'll love the game.
I was a huge fan of Mechassault on XBL, this is about as close as I can get on 360. Its a slower style of gameplay but not as slow as Steel Battalion. The mechs are entirely player built. Unlike Mechassault, you do not simply lock on and fire, you have to manually aim your weapons, with the exception of heat seeking missiles which you only see here and there. Its not quite on the futuristic side, no lasers or anything, there are cannons, howitzers, machine guns, etc.
The campaign tries to prepare you for the online part, but fails. You won't learn too much until you're playing with other people. The campaign isn't bad, but don't expect a riveting storyline. If you're only buying it for the single player campaign, just rent.
I'm actually playing it right now. Just got my 360 back, haven't played since February, and my clan disbanded. I'm trying to figure out who I know that still plays and see if they can weasel me into a clan somewhere, you need to be in a clan to participate in the online campaign. But, you can create your own clan, or just play in free battles if you want.
This was my primary XBL game until my 360 broke.