I just finished the game, and I agree: This is bad, bad writing.
Although you get to "choose" between
two three endings, the choice comes through a stupid deus ex machina (quite literally, actually) at the very end of the game.
Also, they employ a reality which was completely absent in the three games to shoehorn this "choice" in. This is not about a "sad" or a "happy" ending, this is about an ending that has zero to do with the series. There can not be a feeling of accomplishment for the players. Bioware is now taking a beating because fans demand a "happier" ending. I think what they REALLY want is one that actually makes sense.
Lastly, who survives and who doesn't depends on a certain score which seems to be massively raised through the stupid Origin multiplayer mode. I did whatever I could to raise this without the multiplayer, and I thought I did things pretty perfectly. To no avail.
A failure for the ages, unfortunately.