One of the few games that i have thought 'just one more mission', and next time i look up, 3 hours have passed! Get it!
The mechanics work brilliantly, and weather you are in a Vital Suit or on foot, the game feels totally accessible. The difficulty is great, while Easy wont be much of a challenge there are times that you will have to retry sections. But when you get onto hard, the game really becomes fun... you jump in and out of vital suits so quick, and only then do you truly appreciate how much of a life save the grappling hook is!
The balance of Akrid and Human enemies feels good, and you will soon learn to hate both... it would be nice to see a little more types of Akrid, but you cant have everything.
A definite buy, even if you dont have XBOX Live, the campaign if good enough that you want to replay it, even without the added lure of the Target Markers and Achievments.