I read Half-Blood before I read this, and I must say I did see some similarities and I can understand people's anger towards Half-Blood. However, that didn't stop me enjoying either books and I really enjoyed both.
I enjoyed the characters in Vampire Academy. I loved Rose's loyalty towards Lissa and I really enjoyed their friendship. However, sometimes I didn't really like Rose. She's not one of those characters you instantly like, but she does grow on you. Rose was brave, independent, tough, and a bit bitchy, but she could defend herself. I also liked Dimitri, and his relationship with Rose, and I enjoyed the development.
I don't really read many vampire books, like, really little vampire books, but this is different and vampires were twisted into something intriguing and interesting.
I would definitely recommend this book.