just got done playing through every mass effect game, below are my thoughts on 3 as it is still fresh in mind
the good:
i greatly enjoyed the combat and feel that it is the best of the series its fluid and faster paced, way, way more weapons, no arbitrary restrictions on what you can or cannot use, the powers are very fleshed out and fun to use regardless of class
the consolidated paragon/renegade morality system is how it should have been done from the beginning giving greater opportunity for roleplay and actual decsion instead of blindly following the pre-determined paths
killing 300,000 batarians is made canon, the objectively best part of mass effect 3
the bad:
cerberus fighting against you from day one is so out of character it feels like the writers at bioware hated that anyone even remotely agreed or liked them and were like 'NOOOOOOOOOOO! YOU CANT LIKE CERBERUS THEY'RE EBIL SPACE NYATZEEES!' despite the fact cerberus hasn't done anything any other race's black ops hasn't ro wouldn't given the opertunity, looking at you STG
the squadmates are lifeless and uninteresting, further more there is literally no reason to speak to any of them, unfortunately even garrus is significantly less cool than in previous games, for a game series that is at bare minimum 50% character focused tanks the experience beyond words
ironically the game with the best version of the morality system is the one least equipped to exploit with it, every dialogue option is paragon or renegade, upper right or lower right, no neutral options at all, maybe its because the writers were fed up with people only really going for paragon options that they threw up their hands and said 'why even fucking bother?'
the side fetch quests are me2's scanning for upgrade materials but somehow even less engaging and more annoying
legion is killed off for no reason
no exploration of the effects of indoctrination on a galactic war, given that any exposure to reaper tech leads to indoctrination