The casting is excellent, isn't it? All of them! Alan Rickman could not play Snape any better than he does. His voice, facial expression, pauses, and body language are perfect! Knowing what happens from reading all the novels fills in some blanks and makes everything foreshadowing. I hated for the books to end and look forward to the next movies and dread having it all to be over. It's been long enough that I can read them again. I'd like to have the British versions and can order them from the Canadian Amazon.
Here's some of what Roger Ebert wrote in his review.
In one of the opening scenes, we find Harry (Daniel Radcliffe) late at night in a cafe of the London Underground, reading a copy of the Daily Prophet which poses the question: Is Harry Potter the Chosen One? By the film's end, he acknowledges that he has, indeed, been chosen to face down Voldemort (whose name should properly rhyme with the French word for "death," mort; also, since their word vol can have meanings such as "thief" and "steal," Lord Voldemort is most ominously named).
There are really two story strands here. One involves the close working relationship of Dumbledore and Harry on the trail of Voldemort. The other involves everything else: romance and flirtation, Quidditch, a roll call of familiar characters (Hagrid, Snape, McGonagall, Wormtail, Lupin, Filch, Flitwick and Malfoy, whose name could be French for "bad faith"). With names like that, how do they get through Commencement without snickering?
Some of these characters are reprised just as reminders. The giant Hagrid (Robbie Coltrane), for example, turns up primarily to allow us to observe, look who's turned up! Snape, as played by Alan Rickman, is given much more dialogue, primarily I suspect because he invests it with such macabre pauses. Radcliffe's Potter is sturdy and boring, as always; it's not easy being the hero with a supporting cast like this. Michael Gambon steals the show as Dumbledore, who for a man his age certainly has some new tricks, so to speak, up his sleeve.
I admired this Harry Potter. It opens and closes well, and has wondrous art design and cinematography as always, only more so. "I'm just beginning to realize how beautiful this place is," Harry sighs from a high turret. The middle passages spin their wheels somewhat, hurrying about to establish events and places not absolutely essential. But those scenes may be especially valued by devoted students of the Potter saga. They may also be the only ones who fully understand them; ordinary viewers may be excused for feeling baffled some of the time.