Finally beat ME3 yesterday (late to the party, I know... playing FFXII-2). Enjoyed the game, don't understand all the hate against the ending (c'mon, I can name countless games with far worse endings!). I'm not bothered by the Tali reveal, and she's still the greatest character in the series, IMO. Overall, not as amazing as ME2, but probably not for the same reasons people are saying.
My biggest gripe with the game is the move back to centralization. I loved ME2s decentralized feel, you have a number of different "home bases", that you get to play around in. Omega was especially cool, but the Asari merchant planet was breathtaking, and there were a few other smaller ones too. The citidel got old, I wanted more varried community locales. On the same note, I wish they had changed things up a little more from ME2. For instance, I liked the concept behind the Mako driving sections in ME1, but agree that they were poorly executed. I was hoping they'd have something a little similar in ME3, but maybe with the Kodiak's... instead of just the boring planet scans. Too many of the side missions were just planet scans, instead of raiding bases or rescuing people, it made the game feel rushed out the door.
That said, I enjoyed the experience. Not GOTY material like ME2, but great none-the-less. And *GASP* I'm okay with the ending as is, I know I'm in the extreme minority, but I actually think it fits with a lot of the themes of the series. Well, at least it was a hell of a lot better than the ending of Fallout 3, but I know that's not saying much.