The game is NOT an FPS. Its, as you said, a third person shooter/strategy with RTS elements. Personally I can't stand RTS's, but this game is the perfect blend of shooter and strategy elements.
I just got through the first couple campaign levels and its easy to pick up. The basic jist is you control one main troop (you can switch to any troop member) and control your squad to reach checkpoints. You can select either specific groups of units (like all your mechanized armor, all your infantry, etc) or all your troops and select a goal to control or target for them to destroy. You can also have them wait or follow you.
The graphics are pretty decent compared to what I'm used to on the Wii, nothing really mind blowing. The controls are actually quite tight and I'm getting the hang of in combat run/shooting and dodging and strafing with no difficulty. I haven't tried online yet as I don't have time, and I'd imagine I'll get my ass handed to me.
Anyone on the fence I'd say go ahead and buy it, especially if you have the other AAA wii titles already, its a great one so far.