Having replayed the MSQ on my alt, I can definitely say it's not perfect - Garlemald's arc rushes to a conclusion, Elpis runs at a slow pace, and everywhere else seems to be rushing, dragging, or both. Labyrinthos especially, where the end is nigh... so you run around Sharlayan's bunker with occasionally philosophizing moon rabbits.

That said I have to agree that the discontent is pretty concentrated on the official forums, mostly from people who liked the Ancients and were dissatisfied with how their end was handled, or otherwise want / need character death(s) for emotional torque. Elsewhere it's overwhelmingly (though admittedly not universally) seen positive reception. There is such a thing as overanalysis, and subverting expectations doesn't always play out the way you want it to.