I loved Mass Effect 3, and the rest of the ME trilogy as well. I didn't hate the ending nor did I love it. I enjoyed the philosophical aspect of all three of them, but what was disappointing to me was the following:
1-I would've loved to coordinate more of the "final attack" on Earth, just like we did before during the suicide mission at the end of Mass Effect 2. I think that by just having drell, elcor, krogan, among others, fighting alongside each other would have done wonders to the last mission, as it would've have given us gamers a sense of satisfaction witnessing the whole galaxy coming together as one to take down such a powerful foe.
2-I, like so many others, wanted more closure with the other squadmates of mines, most notably those from ME2 who were largely regalated to cameo appearance or very small yet vital roles. I loved the fact that I got to say "goodbye" to Liara, Garrus, Javik, Wrex, Tali, and everybody else, but I felt that doing so with my other ME2-centric squadmates such as Jack, Grunt, and Miranda felt hollow and discoonected. I'd also like to point out that we never find out how our crew got back on the Normandy or how Joker decided to leave the fight, abandoning the fleets and Shepard back on Earth. That's very out of character, although Joker fighting to save the ship from the blast was admittedly nice.
3-The end cinematic for all three choices at the very end of the game were too similar. Making them more different would be great. Also, it'd be nice if you guys could add a epilogue of sorts to wrap up all the plot holes. I'm not asking for a Fallout 3-esque epilogue that's basically a slideshow with a narrator or a MGS4-esque epilogue that stretches out for nearly an hour (although Kojima did do that epliogue masterfully), I just want a Halo 3-esque epilogue where we everybody mourning the death of the hero, where we see the impact that our Shepard had on the galaxy, how the races are coping with the defeat of the Reapers and the destruction of so much that they loved and cherished. Have Liara or whatever LI the player had talking to the son or daughter they had with Shepard. Let our LI tell be the one to tell Shepard's story. I find that that would be more emotionally satisfying than the Stargazer talking to one another.
4-Wrap some of the plot holes that were neeedlessly brought up by the Catalyst, most notably its reasoning that organincs and synthetics can't co-exist with one another. Most of us have just made peace between the Geth and the Quarians, (synthetics and organics, resptively) and we have also shown E.D.I. that "true" meaning of life, of love, of free-will, yet this omnipotent, transparent child tells me that its simply impossible for us to co-exist? No, I can't have that. There should be an investigative-type of conversation with the Catalyst where I can make it question its own logic because its logic is very flawed. Very flawed, indeed. I want Shepard to be defiant because he's always been that way. Shepard's not a "yes man" who agrees to anything that people tell him to do. Shepard's got a mind, a voice. Let him/her use it.
5-One thing that irked me throughout the whole game--and especially at the end--is the absence of Harbinger. I mean, he was so threatening throughout ME2 that I thought he'd have a larger role to play in this concluding chapter of the ME trilogy, considering the fact that Harby is the leader of the Reaper armada. It's shameful that Lieutanant-Bastard Kail Leng had more of a menancing role than him. I rejoiced when Harbinger was leaving the fight and coming back down to Earth in order to stop me from the reaching the beam. Yet when he arrives, he says nothing. Harbinger saying nothing? Seriously? This bastard never shuts up, but when its finally time to see him, up close and personal, he says nothing? That's disappointing. Make him be his usual cocky, condenscending self. I want to hear, "You have failed, Shepard!" or "Your efforts to stop us have been in vain, Shepard. Your end has come!" I don't know. Something like that.
6-I don't know what the new DLC is going to add/alter to the original, canonical endings, but I would like to see you brilliant minds at Bioware add an entirely new "happy" as well. Make it the hardest one to get. I don't care if its required to get 10, 000 EMS in order to achieve it, but it'd be nice to have an ending where everything goes the way we planned: the Reapers are destroyed, Shepard lives alongside his/her crewmates and LI, and the rest of the galaxy is seen recovering with the tone of prosperity and peace in the air. Show Shepard with Garrus and Jacob at the bar (they owe a beer, if I recall) or Shepard collecting seashells at the beach with his LI and kids (its very cheesy and corny, I know, but its what Mordin what would've wanted.
Everything else about the game was practically perfect (except the journal and side quests). and I commend you guys for creating the greatest series that has ever graced the beautiful medium of interactive art known as videogames. You guys, and whatver you end up doing, have my full support. I'm perfectly fine with how this game and this series, as a whole, turned out. Unlike so many others, who are very rude and unappreciative of what you've given us, I thank you. I sincerelly do. You've given me one of the most profound and personal experiences that I've gone through in my life. No matters what happens, let it be known that you guys at Bioware are the best in the videogame industry (with Kojima Productions right behind you) and that all of this negative reaction, whether it'd be geared towards the [optional] homosexual relationships in the game, the Day-One DLC, or the ending (s), is completely unfair and unwarranted. I wish you guys the best, and I look forward to any--and all--that you intend to release for ME3 and any other projects that you might make in the near-future. Cheers--and thanks for listening to all us, like always!