I haven't done ending Y just yet, but I've finished through the core 5 endings. I enjoyed it, but it wasn't something that resonated with me quite as much as I thought it would. I just didn't take to a lot of the music, and it actually got a little tedious listening to it by the time I was in Route B, but I started liking it more due to the changes in motifs with Route C. I just didn't need vocals in everything, be it fighting in random battles or just going from point A to B in town areas.
I didn't mind the side-quests, as they can be pretty rote in any kind of RPG so it was standard fare here -- but I found the conclusions of most of them to be a bit, I dunno, trite I guess. Fight dojobot to the end, and he finds death the fitting conclusion; race racebot and beat him, it then decides to blow up; repair the Engel goliath, it gets bored and decides to die; whimsical philosophical bots all staring off on the edges of heights, they decide to suicide. Like, alright I get it. Not to mention 9S being all "huh?!?? machines with feelings?!??? nah... can't be..." to every occurrence.
Which, I find the characterizations of 9S and A2 amusing in that regard. 2B is generally objective-oriented but 9S and A2 being all "DESTROY ALL MACHINES, NO EXCEPTIONS" only to be all "well some machines are ok i guess" 5 minutes later is a hard one to swallow, especially with A2.
I think some of the harder hitting moments were less impactful for me because of the intro sequence. When the start of the game has your main characters suicide bombing and regenerating into new bodies, it framed the events later on in a way that made them less emotional. I actually found it outright goofy seeing 2B strangling the corrupting 9S, I mean, that's gonna kill an android? Well alright.
Still, game was real enjoyable overall, and the only thing stopping me from diving into ending Y right now is how tedious I feel getting all the remaining weapons then upgrading them will be. The ending E credits were a real treat. Admittedly, I'm not really sure what sense to make out of the post-credits scene.
All that said, playing this has gotten me intrigued to actually play the original NieR, which I've had a copy of for years now but never started playing. Some of the imagery and words dropped made it clear to me things were being called back to, and if the pacing of Automata is any indication of how the original is, then it won't be as difficult to motivate myself to play it as I thought it would.