Gekka Bijin, or Maison Plaisir, is a mediocre hentai story-wise:
It's about Seiichi Itoh, a new tenant in Miyuki's, the landlady, boarding house, and how he manages to find some hidden secrets related to his past, the landlady, the other residents, and the boarding house itself while living there. Obviously, the secrets are X-rated, but I won't spoil them for you.
Art and animation is pretty nice compared to all the other hentais out there. The depiction of the sexual scenes is pretty good overall, just like the drawings of the surroundings and the characters, per se.
Sound is decent, enough as to be listened to, at least.
Character development... For being a 2-episodes hentai, it's decent. You get to know about the past of at least the main characters. It's not that their stories are very believable, but hey, it's a hentai so let's not expect much!
Overall, if you like hentai, you'll enjoy watching this series, at least for the sexual scenes (Uncensored, obviously).
P.S.: For the producers, just because it's a hentai, it doesn't mean you don't have to come up with interesting stories! Come on, gives us hentai series with good, well-developed plots!