I have a strong love-hate-hate-love relationship with ME3.
When I first started ME3, I loved it. Looked great. Played great. Rannoch was amazing. Tuchanka was amazing. It was all coming together, I thought. I missed vehicle sections and the quest structure was weird, but at the same time I appreciated not having to slowly scan for minerals or do time-consuming hacking minigames.
The ending, of course, hit me like a load of bricks, and I still detest the original ending. It can't be overstated how bad it was that it took someone like me who held Mass Effect as his favorite series outside of Zelda, going into ME3 eager to replay the series over and over to see all the different permutations, only to lose almost any desire to play any of the games again.
But while I made my displeasure with the ending known, I also was totally up for their attempts to address the biggest problems with the Extended Cut and to give us great DLC to plug up some holes. And, in my opinion, they mostly succeeded. Now, I still don't think it's perfect now, by any stretch of the imagination. It's still the weakest finale of the trilogy and the ending scenarios still suck, but while it may still lack narrative sense, it gave back what was more important and lacking the first time around: EMOTIONAL closure.
And by the time Citadel DLC hit... Bioware "got" it again. I wish, I WISH, the Bioware that took that feedback from ME3 and gave us Citadel could give us another stab at the endings from ground zero, because I'm confident they'd get it totally right, but as is it's still not awful. They salvaged an "F" conclusion and turned it into a respectable "B" ending.
And, more importantly, the fondness I have for the journey and the trilogy slowly returned. I bought my best friend an Xbox 360 and the games so she could enjoy it. I watched my wife play through it eager to find out what happens next.
ME3 had an impossible task of making "every" choice matter, and only managed to make 50% of them stick. But... those 50% were GOOD. For every "kill or spare the Rachni" invalidation, there was the choice between the Geth and Quarians on Rannoch. For every "Udina is the councilor regardless" moment, there was a Genophage mission. For every "mundane fetch-quest" there was a "shoot the bottles with Garrus" moment. Priority: Earth still is the most unenjoyable section of gameplay in the whole series, but I couldn't put my controller down when I was watching Palaven burning, or racing through the Salarian labs to protect Eve, or dodging Reaper blasts to summon Kalross.
ME3 is a game of peaks and valleys. I honestly think it has the highest highs of the entire franchise, but also the lowest lows. It's a game of extremes that, through a LOT of time and effort and through a hail of criticism that would cripple and demoralize any developer, they pulled it together, picked themselves up out of the dirt, and ended their development with the greatest piece of Mass Effect content we'd ever receive.