With Harem type anime being a dime a dozen now even the good ones fade into the crowd of all the mediocre/poor ones. Harukoi Otome really stood out in many positive ways, while only having one real negative aspect - it was too short.
Basic storyline is very similar to Da Capo and Shuffle; with the focus of the story being around a brother-sister pair that fall in love with each other, but aren't related by blood. The relationships are near xerox copies of the ones with Naru in Da Capo, and Kaede in Shuffle down to the same circumstances that brought them together.
The beginning starts out with Umi getting really mad at her brother for reasons he can't understand. Throughout the anime he speaks with his friends and many of Umi's friends to figure out what's going on.
While there are still plenty of h-scenes and the animation is very well done, they take a backseat really to the actual story. I frequently found myself more interested in what the characters were talking about during the h-scenes than the actual action.
Character designs are beautiful, though not distracting in any way its struck me as strange at how exceptional the artwork was for an ecchi anime. There are plenty of hentai/ecchi anime out there with good animation quality, Harukoi Otome has that but its the character artwork itself that is a real treat. Was a real surprise, usually only see this level of artwork in bigger budget OVA's or movies.
Character voices are all really well done and are a good fit with the character's personalities. Much of the anime is plot drive, but doesn't have much background music of note. Much of the story is revealed during the h-scenes while the characters are speaking to one another. Everything is clear despite what other actions they may be doing at the same time. Didn't find myself having to pause or playback scenes in order to hear important information that was muffled or otherwise obscured by moaning.
There really aren't any two characters that are alike, some are similar but the cast is very diverse. For an anime so short there is a lot of character development (though it happens rapidly) with the main characters. Several of them have really painful secrets revealed that I found touching. Not something that normally happens in any anime so short.
There were a few places that really made my scratch my head thinking this makes absolutely no sense: "Take my virginity and I'll give you the information you're looking for". Had there been a few more episodes those character relationships may have developed to the point where that would've made some sort of sense, instead some things come out of left field completely unexpected.
Eroge to anime adaptations don't have that great of a track record. There are a few exceptions out there which can be counted on one hand though. After the first few minutes and seeing the amazing artwork the story became more interesting than the hentai aspect of it. The h-scense aren't bad or distracting by any means, just not the main focus.
Harukoi Otome (loosely translated 'A maiden's first love') is one of those rare hentai anime that I found myself watching primarily for the plot. The main downside is that its too short and you're left wanting more. I think this series would be perfect to expand to a full length series and adapt it in the same manner that Da Capo and Shuffle were.