For a game proclaiming that your choices mattered, and that you were able to shape your character over 5/6 years and 3 games, to come to the end and be presented with three shades of grey did not sit terribly well with me. I didn't particularly want a happy ending, until I realized that I couldn't have one, under any circumstances. For a game of ME's ilk and nature, all outcomes should have been possible on a sliding scale, and the decisions you made during the trilogy, during PE, and on the Citadel at the end all should all have factored into the outcome.
Casey told us prior to the game's release that we wouldn't be given an A, B, C ending - no, instead we got the red, blue, green ending. Yay!
I guess the easiest way is just to play Shepard as renegade. In that scenario you can't lose;
Control - Yes! Got myself control of the mighty Reaper war fleet, right let's take the armada to the nearest system so that they can pay homage.....or die.
Synthesis - Kerching - Space Hitler Shepard gets to create the new Master-race by space-raping all life in the galaxy via space magic.
Destroy - Win! <but there's a possibility that you might have to commit genocide against the Geth, and kill one of your own squad>
Refuse - Everyone dies. That'll teach them all for not believing Shepard until it was too late.
OTOH, Paragon Shepard is screwed.
I really don't see why they didn't just expand upon the high EMS destroy ending and show Shepard clearly surviving. Those who want a more upbeat ending can have one. Those that don't care, well just pick whichever one you want, there's plenty of misery to go around.
The reason is that BW know that Shepard surviving in one scenario is going to lead people to pick that scenario over their own pet ending - synthesis. Only trouble is, destroy is by far and away the most popular choice anyway, with synthesis being the least popular.
You and a lot of people missed one very important thing about Me3: the running theme through the entire story, in every mission -- even the Omega DLC, in fact -- is the redemption of heroes through self-sacrifice. Mordin (and possibly Bakara too) gets himself killed to cure the genophage (or doesn't, and agrees to screw over the Krogan for now). Legion sacrifices himself to give the Geth all intelligence (and maybe Tali kills herself if things end badly).
In the end, Shepard can either make the ultimate sacrifice to save everyone and make the world a better place (like Mordin, Kaiden/Ashley, Legion, Nyreen, etc) or he can screw over everyone and accomplish his mission and restore the status quo. That's really the choice you have: be a live soldier who accomplishes a mission or a dead martyr who changes the world.