As you well know Crippollo, Halo Wars is not a FPS so it cannot be compared with the other games in the series (whether Halo3 sucks or not). I haven't had the chance to play it yet, but I bought it for the kid as soon as it was released because he loved the demo. He says that the full game blows the demo away and I watched him play some and it appears to be the best RTS on any console.
It doesn't really surprise me because (as very few of you might know) the Halo franchise started out as an RTS game at Bungie a decade ago before morphing into the FPS juggernaut we all love/hate so much. Plus the game was developed by Ensemble Studios, the creators of the Age Of Empires series on the PC, who knew what they were doing.
From watching Aidan play, it appears that the control scheme is slightly better than Command & Conquer, Battle For Middle Earth or Supreme Commander and is much better than Civilization Revolution and Endgame. Selecting units (A button or LB or RB), moving or attacking (X button), secondary abilities (Y button) and unit/structure creation (left stick) is simple with virtually no learning curve. The kid says that there are some minor AI & pathfinding issues, but what he likes the most is that it still "feels" like a Halo game.
I hope to have the chance to give it a go when I get back from LA next week, but from watching him play and from what he tells me, I'd say it's well worth the money if you are even remotely interested in RTS's. If you like the Halo universe as well, then it's a no brainer.