Watched this movie last night on my flight. It is darker than the other Harry Potter movies, but I thought it is very good.
Its basically more of the same in that its Harry vs the forces of Lord Voldemort. He has been building power and he is certainly making it harder on Harry.
Some of the magic appears to be gone. Some of the fun things of the original movies, learning to fly, quidditch, the new discoveries as he learns magic are gone. Instead we are to the nitty gritty of the storyline.
I'd certainly strongly recommend seeing the earlier movies before delving into this one. But for Harry Potter Fans, I think it lives up.