* Prices may differ from that shown
I thoroughly love this game I have all versions on the PC and can not believe the scale of maps/units and battles there are. I then got this game for the Xbox as I could not always have access to the computer to play the PC version and the fact that I like earning achievements as well.
However the first problem I could see with this game is that the controls are clunky and loading is very slow. This are two key things that need to be right with a real time strategy as wasted time means your at a disadvantage to your opponent. While you can still have good games on small maps and still earn achievements it is more time consuming playing on the Xbox and most games end with nukes firing, as the game can not handle a large army or it will grind to a halt.
The main reason it is not very fast is the fact that the game was built for the PC first then transferred to the Xbox which meant controls were converted not created. This game is fantastic on PC and if you want to try a large scale RTS with the need for planning and tactics get it for the PC.
That being said with the recent-ish release of the second supreme commander title the console version is much better, as in that case the game was built from the ground up on the console.