I generally enjoyed the game up til the end, but yeah.. The final half hour kinda left me with mixed feelings.
I think the problem is that instead of pandering to fans, Bioware did their own thing. Usually I'd think trying not to pander was likely the better move, but given the emotional attachment people will have to their Shepards by this point anything less than a happy ending was going to give that favourite toy just run over effect Zekester mentions above.
I mean, as Shepard you've basically been fighting the inevitable, trying to overcome fate, but when you face the source of that fate you are forced to comply with the options it presents you. All of them being varying levels of bleak.
The God Child's whole argument is flawed though, in my play through Joker and Edi became a thing and the Quarians / Geth allies - suggesting that the created will not always rebel against the creator. It's also ironic that the solution to this problem is to kill off organic life before they can create self aware AI - with self aware AI.
There was clearly potential for Shepard to give one to the God Child, but we weren't ever allowed to, and had to accept fate - as mentioned, what we've all been essentially fighting against. There's a few plotholes in the ending also and pretty grave points that aren't covered or explained. I don't think they're as much of a problem.
I feel if they offered more choices everyone would be ok - I mean, one or two 'good' endings where Shep lives and all is happy, available by doing amazingly thought all three games, with another one available by doing 'ok' but potentially resulting in Shep's death, then the 'bad' ending where Earth goes up in Flames, Shep dies etc would have been good. Even then perhaps add a bittersweet ending where you did bad, but if Shep gives up his/her life you can still save everyone else.
Dunno, my opinion really. I do think Bioware shouldn't have forced the Martyr status on Shep though, the whole thing is just a bit too self indulgent. Maybe played the martyrdom card too often - Mordrin, Kirrahe/Thane, Legion ( or Tali... But that's more plain suicide.. ). There was a bit of a theme where characters sacrificed themselves to varying degrees of glorification. ( edit - Also Cortez, although I'm pretty sure Cortez intended to keep living )
Other than that, I did notice the lack of 'roleplay' in the game - most choices were either paragon response or renegade response, with no neutral ground. Plus I feel I'm wrong but still, it did seem that the Illusive Man got half of the persuade / threaten lines, with a good run of those squeezed into the last 10ish mins. I can understand that there was a lot to get through and a tonne of loose ends to tie up, but still.. I wonder if we could have got the chance to debate the point with the God Child if we were still playing by ME1 writing agendas.
The game was good though, overall. Few polish issues but nothing game breaking.
But as always, just my opinions
not thinking objectively, of course.