ME3 Ending is what gaming needs
Many people are be moaning MassEffect 3's ending, often full of all kinds of independent assumptions, incomplete information, and just WRONG data (see http://www.gamefront.com/fans-write-comprehensive-take-on-the-me3-endings-logic-problems/). I say, this is the kind of story telling that gaming needs: high sci-fi, along the lines of Heinlein or Clarke. Writing that makes you stretch your imagination and waxes existentialist.
While I understand what many are saying about the character of the Catalyst (introduced in the last 5 minutes), I don't think it's a legitimate complaint, respectfully. This is the kind of thing that good stories do; turn what you thought you knew on its head; make you think about the entire story in a different light, and make you (or the main character) reflect on themselves in a new light.
The end-goal to the entire series was the defeat of the reapers. Nothing else mattered. Sure there were interesting story arcs that paved the way to that goal, and cool, valuable, sympathetic and empathetic characters that you (and I) as the player become invested in. But they were always a means to an end, and the ending the devs gave us shows that. It FORCES the player to realize something that the ENTIRE story was about: sometimes there are no good choices. Sometimes winning entails loss. Shepard had to die, and something else had to go as well.
In the red ending, the reapers die and Shepard dooms the universe to organic extinction by selfishly refusing to accept the reapers and the Catalyst like she has forced the Quarians to accept the Geth, or the Krogans to accept the Salarians, and so on.
In the blue ending, Shepard again dooms organic life by egotistically thinking she could succeed where the greed of TIM failed. That she could control the Reapers.
Finally, in the Green ending (the one my Shepard chose), she realizes that the galaxy as a whole, as it stood, had to die with her in order to survive. She had to accept the reapers into herself, and every other organic species, to save existence.The Catalyst worked the same as many such beings have in MANY other stories: it forces the reader/player/protagonist etc to face their enemy on a while new level. A level that mirrors the rest of their struggle.
But good stories don't have clean endings. The greatest stories are those that emulate real life: they are messy, and not always closed cases. The reason so many people are angry is because it was not a closed case. You weren't the guy from MW3, smoking a cigarette, staring at the body of your fallen nemesis as you pass out and likely die. You aren't a newly-minted Jedi, mourning the death of your father as he and your teachers smile down on you. etc. It's like HL2 Ep2, it's like watching Frodo and your favorite characters DIE at the end of LOTOR, or any one of a myriad of famous classic stories: the ending is raw and somewhat open ended, and as a result, the player CARES and CONTINUES to. The caring does not end with the story. Their emotional investment, just when it is waiting for some great payoff, some expected end, it's denied that, and we react emotionally. That's just good story telling.