The opening sequence set against the wonderfully macabre backdrop of Mexico City's Day of the Dead is one of the best in the entire Bond series. The first shot which follows Bond through the packed streets has to be by far the longest shot in Bond history lasting for a couple of minutes, setting up the film impeccably.
The action sequences are of course the highlight of almost every Bond film and there are some fantastic ones here. A vicious fist fight on a train with more than echoes of a similar fight in From Russia With Love is perhaps the most memorable. Also one of the best parts of Spectre is the rest of the MI6 gang's escapades; Q (Ben Whishaw), Moneypenny (Naomie Harris) and M (Ralph Fiennes) have perhaps their most adventurous outing yet, besides the previous M's fate in Skyfall. Ben Whishaw's Q is a scene stealer, with his geeky charm and boyish innocence, a fantastic foil to Bond's experience and grit.
A major problem I believe with the Daniel Craig series of Bond's is the villains. It's not that they are bad, but they hardly figure in each film. Christoph Waltz is brilliant as Franz Oberhauser, but he only seems to have 3 or 4 scenes. When you have as good an actor as him you would think they would make the most of it.
I also still have a problem with Craig's version of Bond. Is he a brute in a suit killing his way around the world without a second thought or is he actually a deeply troubled soul struggling to break free of his profession? Of course it's great to have nuanced characters, but Bond seems to flip from one extreme to the other in a matter of seconds; speaking candidly with a beautiful woman than breaking someone's neck at the end of the sentence.
I suppose it doesn't matter, Spectre is still a thoroughly entertaining action film, and to give Bond too much scrutiny is to miss the point really.