Look, I'm terribly sorry.
Yes, some of these actors seemed to be BORN for these parts (Snape, Lestrange)
But, my god, total hackjob. The past three movies have practically eliminated all of the subtext which made them, and book six (and I hope seven) so special.
Yes, Umbridge was a big part of the fifth book, but so was Snape, and Malfoy. In fact, Snape and Malfoy have been big parts of all the books for a reason, because I'm sure they will factor into seven as they did into six. Rowling has been building these characters in her head and books for going on twenty years now, she knows what she's doing, and in the books she has space to do so.
On the screen, no time is provided for back characters, everything needs to focus on the major new events (the Triwizard tournament, Umbridge) and the regular characters are completely written out. But they're the ones who will tell the final story, mark my words. Unfortunately, by the seventh movie, I'm afraid anyone who didn't read the books simply won't have the backstory to give a hoot.