Spectre itself, good idea, worked well, interweaved well, enjoyed that concept. Bond going rogue again at the start, seen it a few too many times now. Rehash. Threading back through previous deaths, the reemergence of Mr White, enjoyed that also. the fact someone was spinning the whole thing, playing James along, fine, happy enough with that.
Where I think the missed the mark, was in the culmination, building it all towards this hatred, this question of will he kill him, or let him be captured for information, I just didn't buy it. Even after threading the whole of his life, taking out Vespa, ending M, the Quantum business, fine, but in the end, given who bond is, given the lead up, I think when it comes to shooting the guy, and the big decision to make, I feel simply wouldn't care.
He's a sociopath, a cold hearted device, danger all that in front of him, won't make much of a difference, if big picture means keep Blofelt alive, he simply will. Any other protagonist might shoot (Brad Pitt in se7en built this same premise) but not Bond. He'll kill if he too, won't if he doesn't.
I think it is in this that the film fails.