I can see why people didn't like the ending. After all the decisions you have made, the ending seems to not exactly be the culmination of these experiences. But to those people I say: You are expecting too much! And what's more, you are expecting too little!
Mass Effect is renowned for making you not only make average decisions, but some really tough decisions. The ending of the game is not an insult to the series, in fact, it is the pinnacle of making hard decisions. I for one, thoroughly enjoyed making the decision.
So to everyone still wondering, and for some this review probably has come too late, this game is epic, well designed, cinematic, glorious, and to top it off, has an amazing story and an ever better ending. I am sad the journey is over, but at the same time I am happy it has ended. Onto bigger and better things! Dont be afraid of a series ending! It only opens the door to better things!