I'm not going to go in depth here, but essentially, Mass Effect 3 is a mostly disapointing finale to the trilogy. The game lacks RPG mechanics and dialogue choices. On a whole, it feels more linear and driven by combat, rather than primarily focussed on interesting storytelling or character building like the previous two entries in the series. Your decisions in this game (and decisions from elsewhere in the trilogy) feel inconsequential here, and the ending is thoroughly unsatisfying. After all these years, I'm still bitter about it.