Great read, and easily one of the best romance manga I've ever read. I'll be upfront and say that the premise of the story is not for everyone (personally, I didn't have a problem with it), but it's an integral part of the narrative and the driving force behind everything that happens. It never once feels tacked on, and as long as you're not bothered by it I think you'll find you're in for a wonderful read.
The author takes on a very touchy subject matter in a straightforward and believable manner. This is drama, without all the cliches that are normally found within the genre. Through the course of the story you see these two characters as they run through the whole range of emotions as they try to deal with their growing attachment towards one another, both understanding how society would view their relationship, and yet each unable to rid themselves of their feelings for the other. In truth, and at it's heart, it's a very sweet, very romantic story, one that left me rooting for the couples happiness despite the unconventional pairing.
The story also benefited from a great art style that really worked well in setting the mood. My only complaint here was that the character art was at times inconsistent, sometimes being very well done while others being very sloppy. It was especially disconcerting because this disparity would often happen on the very same page, although to be fair the author seemed to settle down by the 4th volume and there wasn't nearly as much of this from then on.
In summary, I highly recommend this to any fan of romance manga as long as you are not put off by the subject matter. Get by that, and you're in for a treat as this is one of the very best I've read. Sweet, without being sappy, and with nary a cliche in sight. It gets a near perfect score from me, only loosing half a point for some of the inconsistencies in the character art.