Over 700 pages! Enough said on that score.
I don't find the larger than life and ever present Voldemort all that scary. Professor Dolores Umbridge from the Ministry of Magic however is another matter. Her small minded, bureaucratic, saccharin coated meanness is all too believable and I think she is one of the great villains of the series. When the revolution comes she would my choice for first up against the wall!