Although cinemetically pleasing, the film rushed through so many important elements which should have been given more effort.
Blofeld, Bond's lifelong nemesis, the cause of all his pain and the foremost villain in the history of Bond films dies by 'accident' without any intent from Bond, who in fact had his back turned. Just like that. No quip, no fear, no pain, no satisfaction. Even more unsatisfying than the death of Cersei in GOT.
Also, Spectre... the worlds leading underground criminal network, with the world most cunning and evil villain, quickly replaced by another unnamed criminal network with a far less menacing villain. All gassed at a function. Just like that. Oh, and we dont know the background of this organisation, its previous atrocities or much else, other than that its leader lost his family to Spectre as a boy.
So, 'empty' organisation headed by an equally 'empty' villain quickly steals the entire Bond heritage as far as villainy is concerned, and whose evil agenda is also not really known (motive not convincing or explained sufficiently), is thwarted in a strange dance of choreography and unconvincing flow, before its so-called villain is finally killed at the hands of Bond, while grinning, by way of very quick and merciful gunfire.
The way Madelein's "secret" was so hyped up... ooh what is her big secret?? Blofeld: "when her secret finally gets out, it will be the death of you" (yikes! Dun dun dun...)... a few scenes later... Madelein: "oh here's a picture of the bad dude who killed by mom when I was a girl, and then he allowed me to survive, and now 20 years later he apparently loves me and has reached out to me... not quite sure what he's been doing for the past 20 years but anyway..."
So:
Villain = poor
Unnamed criminal network = poor
One action scene with what we presume was supposed to be 'the Bond girl'?
Blofeld death = poor
Plot = poor
No way to kill nanobots? = unrealistic
Bond choosing to die rather than live without coming into physical contact with Madelein = unlikely
Felix death = lame
American villain working for unnamed organisation = lame
And then of course: let's give the movie a sad ending so that we aren't accused of following cliché happy endings...