To me Mass Effect 3 is the best game of all time on the Xbox, having played all three games, the first was good, the second just drew me so far into the plot I couldn't wait for the 3rd and last in the series to be released.
I certainly was not disappointed, I would encourage anybody who has not given it a go to do so, you don't need to play all three games, but with the ability to import your character's progress from the previous game it is worth doiing as the decisions you make in one game will affect what happens in the next.
This week I completed the last achievement to make Mass Effect 3 the first game I have completed in it's entirety, to do this I played it through to the end a couple of times and with various characters, the first was imported the later, was not. This is a great idea as there are a myriad of cut scenes and conversations that come up that I did not see the first time around (when Tali committed suicide I was close to tears!!), but that's the beauty of this game - it's depth.
The second time I completed the game (on insanity) I down loaded the extended cut scenes for the end of the game, I am glad the team at Bioware did this as the original end scenario left an awful lot of questions unanswered, but the upgrade I have to say was more comprehensive and well worth the hours invested in trying to get through on "insanity" (many times the control almost got launched out of the window in frustration!!).
I'm not finished with Mass Effect 3 yet, with the 4th map pack just been released for the multiplayer component I reckkon there are still a few hours of time to be iinvested yet. Well done Bioware for what is truly and epic gaming experience!!