Ok well, for those who know me, I'm sure you already know my feelings on this subject, the Rosario+Vampire manga is one of my favorite modern manga series, and one of the few modern harems I actually enjoy, the anime adaption however comes off as fairly lackluster to me, and well, I hope no one finds this rude or pompus of me, but I feel as if I need to point out why I & possibly some others feel this way. So yes let the rant begin!
Disclamier: The views & Opinions shared in this post are completly my own, and do no reflect the R+V fanbase as a whole.
OK the best way to do these things is to look at all the elements and see how they stack up, lets begin...
While the Anime uses the same characters as the manga its based off of, they come off abit diffrent.
Manga: In the manga the characters while somewhat 1-dimensinonal at first, and obviously based on pre-established cliches/tropes that have been used before, do become well developed characters over time, as the series progresses they grow, we learn more about them and their families, and they become genuinly interesting and likeable characters
Anime: In the anime adaption while the characters have the same overall personalities, they are somewhat deluded, as the characters themselves are genaricized and made more like otaku-bait then actual individual characters at times.
Ok the overall story is basically the same, however the execution is much different. The manga is essentially a modern day Tenchi Muyo, having near perfect balance between Character development & story progression. As for the elements, All the elements are well balanced within the series, the action/adventure, the comedy, the drama/angst/more serious moments, and the romance all work in tandum wiht one another, and even the fanservice is fairly light most of the time and moderate at best, unlike the anime where the fanservice is overly dominant in some episodes (ecspecially capu 2)
..which brings us to the biggest problem overall, the whole reason the anime adaption comes off so poorly is that it takes such a great concept and turns it into another average/sub-par ecchi-harem series. Rosario+Vampire's manga is one of the best of its genre, but Gonzo's anime adaption is overall lackluster & dissapointing. I truly hope it gets the same treatment as Negima someday and gets an adaption more accurate to the origional material and one with better animation.
And now I will admit my overall rant applies more to the second series/season (capu2) more so then the first series/season. Season one did a decent enough job of adapting volumes 1-3 of the manga, but season two is quite frankly where the animated adaption of the series jumps the shark, adding even more fanservice & innuendo then season 1 and further deluding these great characters, turning them into more genaric ecchi gals, which I may find more dissapointing then others as I came into the show reading the magna 1st, and I will admit season(capu) 2 has an EPIC opening, but thats probably another reason it dissapointed me, when you have such a energetic opening as Discoteque and then have your premire ep be mostly frivelous fanservice (mostly Panty shots) it just leaves a sour taste in ones mouth, lol.
So yes, In closing I hope I'm not coming off as too negative, I just felt, that even though overall pointless as it may be I should get my full feelings for the series accross. Now note I'm not trying to discourage anyone from buying Funimation's release of the anime adaption, just mearly stating my personal opinion on it, and warning those that are fans of the series because of the manga (akin to myself) not to expect as much out of it as they have gotten out of the manga.
Depsite all that though I myself will most likely still be buying the show as I am a fan of the series/franchise overall, and even though I dispise Cap 2 (aside from the addictive & catchy as hell op song) I like season 1 well enough for what it is to watch it.
....anywho ah yeah, I highly suggest those who have only seen the anime adaption to check out Akisha Ikeda's origional manga, it really is a modern Tenchi in a way.