Also, where the fudge did all the mechs go in the ~6 months between ME2 and ME3. In 2 almost every encounter features FENRIS, LOKI or YMIR Mechs but they've seemingly all disappeared.
Surely the I-Man would have used mech to support his (presumably VERY expensive) indoctrinated army rather than wastefully throwing them at Shepard like sweets.
Why aren't there Mechs supporting the anti-Reaper forces?
Basically ME3 makes no sense and complete railroads all the choice you made in the previous games in to consequentiality (especially the Geth).
The ending is stupid and disrespectful to the story and the player IMO.
No final battle of any sort, except Marauder Shields.

No decent cutscene of the fleet battle
Why mention the Harbinger being at Earth if he's not going to play ANY part in the game?
Your choices throughout the game have NO consequence in the end, Galactic readiness is irrelevant, just choose ending A B or C :'(
No possibility of having team-mates die through your choices or by not completing quests like in ME2
I didn't need my guns, I could just use powers to win every fight
Day 1 DLC which blatantly should have been part of the game