This is a very funny book. The "true" story of Dracula, told from Dracula's point of view (naturally), the book does not spoof so much as utilize the classic. It helps to have read at least part of the classic (in fact, after reading The Dracula Tape, it may be impossible to read Dracula by Stoker the same way again), but Saberhagen quotes all the relevant passages. I've always been fascinated by the idea of a story behind a story behind a story (What REALLY happened?) and The Dracula Tape is one of the best you-haven't-heard-the-WHOLE-story examples I've come across.
Where Saberhagen succeeds is that he does not simply flip-flop the original, turning Dracula into a beleagured victim, beset by villains. The reader may be on Dracula's side, but you don't exactly trust the guy. Dracula's "voice" is wry, self-deprecating, often annoyed, humorous and cunning. Fact is, Dracula isn't telling the WHOLE story either.