I finished it yesterday, but am only now getting over the shellshock of having witnessed what had been shaping up to be a satisfying conclusion to one of my favorite sagas in gaming implode and collapse in a matter of minutes.
Nearly every fan outline presented in this thread is superior to the red, green, or blue magic laser nonsense we actually got from the Ghost of Vent Kid. I was hoping the post-credit scene would somehow be more meaningful, but "LOL MY SWEET" only made things worse. I'll admit that I'm slightly impressed at how Bioware managed to confuse, frustrate, and disappoint so many in such a short span of time. I wouldn't have thought it possible.
Still, the abysmal ending doesn't change the great moments along the way, (though it certainly makes many of them seem futile). Most of my favorites have already been mentioned: Liara's "Vigil" box to members of future cycles, "I'm Garrus Vakarian and this is my favorite spot on the Citadel", Mordin going out with a song, Tali's reaction to setting foot on the Quarian homeworld and the resolution of the conflict with the Geth, Grunt tearing swarms of Reaperized Rachni numerous new assholes, the fall of Thessia, the list goes on and on.
The constant callbacks to the exploits and encounters of the last two games, and the wonderful banter and interactions among your squad really cemented that they were just that-- your friends and allies that had been along on an epic and memorable adventure that I am genuinely sad to see come to an end. The last exchanges with each of them in London were often poignant, and while the payoff at the end of the journey was garbage, I'll be damned if it wasn't a hell of a ride getting there.