Abloutely awful and pales in comparison to it's manga counterpart.
I started watching anime and reading manga when I picked up volume 1 of Yotsuba&! at my school book store when I was 6. I didn't take me very long to get to the Rosario + Vampire manga. But that's not what we're going to be talking about today. Now, we're going to be talking about it's pathetic-accuse-for-an-anime counterpart.
There is literally no story in the anime. Tsukune Aono is an idiot who is painfully average. Failing all of his High School enterence exams, He has no choice but to go to a strang boarding school, with an application that his father got off the street from a creepy monk. This school is Yokai Academy, a school made so that monsters such as vampires, (surprise, surprise) orcs, werewolves and the like can eventually coexist with us humans, who generally rule the world. Everything after the first few episodes is mindeless filler and pantyshots, with the anime leaving out major plot arcs, even going so far as to cut the real ending, where the manga shined the most, in the epic comfrontation against SPOILER:Hokuto, the head of the student council.
The animation is nothing spectacular, with simple character models, and not much bad animation, but some things are painfully obvious CG, such as the stairs.
The sound is nothing too great. It fits the mood, but nothing is really memorable. The opening theme "Cosmic Love" is quite a catchy J-Pop song though.
The characters have become stereotypes, with Tsukune, a pacifistic twat, Moka "That nice girl", Kurumu, The all-purpose eye candy, Mizore, the emotionless stalker, Yukari, the lolicon, and Ruby, That-one-girl-who's-never-here. Any and all character develepmont has been removed to make room for more pantyshots.
Overall, if you're interested in the series, read the manga and wait for R+V to pull a Kai/Brotherhood and give us a good adaption of a good manga. The anime is downright trash that can make Dokuro-Chan look good. ... All of this and I'm still willing to buy the dub...