Honestly, if you had LIVE your rating would be so much different, just because of the multi-player. It's unlike any online game I've ever played. But the ending did piss me off, extremely I should say, but it lets me know there is going to be Assassin's Creed 3, which is good. And the reason it was so short is it was intended to be an ODST sorta thing. Short, but long enough to perfect the story. Add a new game mode, and add a new feature probable to carry over into the next game. (Body damage after shield loss in ODST, carried over to Reach. Assassin Recruits may carry over to Assassin's Creed 3.)
And Altiar's armor has the same HP as The Armor of Romulus.