Warning: Major Mass Effect 3 spoilers...obviously!
To all the people arguing about the ending, I believe that I can resolve the problem for you. First of all, we all know great movies that we loved and they had sad endings or the protagonist died in the end, so the problem with ME3 is not Shepard's fate in the end; the real problem was with the HOW of it. See, BioWare invested us emotionally against a specific enemy in ME1 and especially ME2, remember the enemy? The Reapers. BioWare also invested us emotionally against the personification of that enemy; remember who I'm talking about? The Harbinger. Think of that and keep it in mind for a while; remember everything that enemy and its personification, your nemesis, did to you, your friends, and your fellow humans. Remember that by the time ME2 ends, we have major unfinished business with the Reapers, and especially with the Harbinger. Now let's fast-forward to ME3 and fast-forward through ME3 too; where are the Reapers? Are they the real enemy that you absolutely hate in ME3? Nope! They were replaced by the stupid, traitorous, brainwashed SOBs, Cerberus, and our fight against the Reapers in ME3, our hatred against them pretty much fades and shrinks compared to how things are against Cerberus. And the Harbinger? Totally, 100% gone, poof, never to be seen or talked to again...magically doesn't even taunt us anymore! And which evil personification, nemesis, replaced the Harbinger? Yep, Elusive Man. But wait...what about the unfinished business with...? Nah, BioWare doesn't care about what they did to us emotionally in ME2. And the worst thing is...in the very end, they don't even let you really hate the Reapers...Shepard is just standing there in front of a CHILD...who is supposedly representing the Reapers and everything they did to you, your friends, and humanity...you see the psychological catastrophe here when they place a CHILD to represent that final moment? And they take it even one step further...they tell you that the BEST and most noble choice is to make nice with them...synthesize, become one with the machines, change humanity into something else, and that's the inevitable ending anyway, so you might as well choose it now. And look, it's really sweet...your pilot will have sex with the robot. That's the major problem with ME3, and its ending, ladies and gentlemenbesides other secondary problems. And why did they do such a thing and really mess it up, thinking that they're ending the saga in an epic, dramatic way? Because the dramatic ending was always there, but got corrupted by the dodgy progagandist agenda of Transhumanism. Unfortunately, ME was hijacked to spread Transhumanism, that's all. I really hope someone rights these wrongs one day, and gives us back the beautiful story and fictional universe we got to know as Mass Effect.