A sadistic church-lady in pink. On a power trip.
I think that an unexpected villain is the scariest, don't you? Say, when a Robin Williams goes all hermit-y, calm, and voyeuristic in a film. It really ups the creep-factor.
The same is true for a comfy, aunty-like woman in pink tweeds with a syrupy smile who has a pen that carves onto your hand whatever you write on paper. Ouch! (It was scarier and more painful reading about it in the book of Harry Potter and the Order of the Phoenix, but it was still hard to watch on the screen.)
My point is, though, that the villain-against-type is more disturbing than anything you need to use "Expecto Patronum!" on. So, Voldemort's a piece of cake compared to Dolores Umbridge, in my humble opinion.
I had two Sunday school teachers and an elementary school teacher that looked just like Umbridge, all perfect twin-setted-up, hair teased just so, neck full of pearls, hands folded like a lady. Fortunately, none of my them had Umbridge's sadistic streak, though they did come across as rather insincere. And were probably leading double-lives as kittens-with-whips.
So, good job, Imelda Staunton, for a very excellent villain portrayal of Dolores Umbridge!
Besides Dolores, one of the best parts of the film was the breath-taking broomstick ride over the Thames through London. Wowser! And it's always fun to see how the cast has grown. Sniff! I'm so proud!
On the other hand, so much of the book (the longest at 800 pages or so) had to be compressed into the film-time that some of the important threads were lost. Guess it had to be done, but I wonder if and how those threads will be reclaimed later. Ah, well. Never mind.
Now, on with the countdown to Saturday, when I'll have to close my eyes and ears to the internet and television until I read the final installment of Potter. Don't tell me the ending!