WHAT DIDN'T WORK
Completely and absolutely everything else. The more I look at it, the ending is riddled with a lack of testing, editing, and peer review.
Let's start with the big picture and point out that, for the purposes of this game, the purpose of ME3 was to assemble the Crucible, because it would do something. The fact that it wasn't a weapon, or a big switch with a sign on it saying "REAPERS", was just fine and I will defend the idea of there being a plot twist. But the plot twist was a deus ex machinae. Literally - the plot was to assemble a computer, and inside of the computer they found a God who can fix everything.
But, on the whole, I could accept this, were it continued in the traditional Mass Effect way. But instead everything is tossed aside. The Catalyst says that the cycle has to continue, but since Shepard is here, that means there must be a change, whatever it is. And Shepard just takes this.
I could see acceptance of this from certain Shepards, but I had played straight Paragon through the whole game. My Shep didn't believe in inevitability or impossibility. There's always a way, and he would find it. But no, instead, he sits there and listens, accepts that the computer will never understand, and picks one of his three options. The fact that we are not even given a choice is the greatest slap in the face of all.
And I understand the futility of it all thematically, but when you start to implement game mechanics around grinding, it begins to feel like a chore, and we wish to be rewarded for our efforts. The fact that it is a yes or no option (Did you get 100% completion? If yes, secret ending. If no, you get nothing.) makes the entire effort of trying to save humanity feel like a waste of time. And not in the cool way, where you realize it was all for naught. It's the irritating sense that, after three games of your choice and work mattering, somewhere a game developer is about to pop out from behind a wall with Ashton Kutcher and yell, "You got punked!"
The reward doesn't even need to be that substantial - just different levels of how screwed the planet is after the fight. If you assembled enough manpower, Earth is saved! If not, organic life is extinct, but hey at least you got those Reapers, right?
But then we get to the part that completely befuddles me, where it cuts to the Normandy in hyperspace (?) where it crash-lands on a jungle planet (??) along with Garrus and Ashley and sometimes EDI (???) and makes some kind of finalized wrap-up, with them starting a new life on the planet (?????).
I mean, primarily, I thought the Normandy and Joker were in on the final fight? How did he get out when we spent so much effort getting *in*. And you can't say that the Reapers died because of your actions, because it all happens at once and there's no way he would be able to Relay jump before the Relay sent the self-destruct signal!
And secondly, what jungle planet, and how did they crash? Where is this jungle planet? I thought most of the universe was explored due to the Mass Relays - wouldn't we know where it is? Wouldn't everyone? And how did the beam destroy all technology in the Red ending, but Joker landed the ship on planet?
And how did my team get onto the Normandy, anyway? The last effort I had Ash and Garrus with me, charging the beam, and everyone but me and Anderson were liquefied by Harbinger's beam. How did they not only survive, but get onto the Normandy before it took off? They don't even have Cortez's shuttle! It makes absolutely no sense!
Even if it DID make sense, did anyone think about what it means? Turians and Quarians can't eat our food. If tech is destroyed, they can't get any more of it anywhere, let alone on Earth or the jungle planet because they can't get home. Hundreds of aliens are stranded on foreign planets, looking at decades of interstellar travel if they survive the initial waves of starvation and panic? It isn't a happy ending that Garrus didn't die on Earth - it's more horrifying that he starved to death on a foreign planet away from his loved ones after his best friend or lover died.
The ending, in short, is completely unsatisfying. While the themes and nature of the story is there, it misses everything else. Narrative consistency. Player agency. Character consistency. Closure in outstanding questions. Shepard bold-facedly absorbs everything told to him, makes a choice that makes the last eight hours meaningless, a god in a box does it all for him, and then we see nothing else of the world we left behind or how our choice affected them. ME3 asks that we allow it to close with it asking more questions than it answers, instead of leaving it ambiguous.
And I say, "Fuck that."
To me, the game is over after Anderson dies. From that point on, Shepard barely hears Hackett hailing him on the radio distantly before he closes his eyes and dies, his mission complete. What does the Crucible do? What happens? Is Earth saved? I dunno, maybe. Let's let forums discuss it, much like the indoctrination theory going on right now.