The ending was underwhelming. I had left the Doom of the World quest alone for about a week as I finished up my side quests and I was starting another new save, so when I finally got around to finishing it, after setting aside a few hours thinking it would be another epic quest. Very disappointed that it was just that one fight. In Hushed Whispers + Champions of the Just were amongst the best quests in the game, and the final one did not match it.
As for the ending itself... it was mixed feelings for me. The post credits scene was alright. It was slightly better and more fleshed out than the original ME3 ending, the one where Joker steps out of the crashed shuttle with your LI and leaving their fates to your imagination. I enjoyed the banquet, and I liked talking to all my companions and knowing that all my decisions mattered towards their final approval of you.
It's not the worst ending around but it could have been better. I had no problems with Corypheus being the main villain as there had already been one major twist (after In Your Heart Shall Burn), to reveal another villain after 100 or so game hours would be comical.