I read it for the first time when I was about 14 and I thought it was very original to make a book out of letters and diaries.
The first part in the Dracula castle was interesting, but then the action got a bit slow. However, I liked the part about the asylum and blood transfusions. Particularly the blood transfusions - all the medical things really frighten me, so it created the proper effect of a horror book
At least it was better than
Frankenstein - that one was so boring I couldn't read more than the first chapter