Unlike the stereotypical yaoi manga, there isn't a whole lot of cheese (or sex scenes for that matter). I enjoyed the fact that the couple was believable (emphasis on couple, as there are a lot of other elements in the manga that are definitely not believable).
I've read a fair number of manga from the mangaka, Yanamoto Kotetsuko, and in general, she does not disappoint. She produces witty, original, humorous, and often touching manga with extremely cute characters.
If you're like me and switched to reading yaoi because of wimpy, crying shoujo protagonists (not referring to all shoujo, just a wide abundance), then you're probably going to like Yanamoto's writing style. Definitely do go check out her other work. If you're looking for an entry point into reading yaoi, I would highly suggest you go for something else (e.g. Totally Captivated, Junjou Romantica, Katekyo!).
If you're reading this review prior to reading the manga, let me warn you that the ending is sudden and severely disappointing. I think Yanamoto intended to end it lightheartedly and have the reader fill in the gap, but there was just an overall sense of irresolution. "That's it?" was my first response as well as many others. I think it was clever to end it at thirteen chapters considering the title of this manga, but there needed to be closure about the condition of Hiroshi's so called curse or "constitution". There is so much opportunity for development especially with Hiroshi's parents, but of course, I understand there are certain limits in the world of manga writing.
tl;dr: The manga is enjoyable and interesting; you should definitely check out other works from Yanamoto; but the ending of Lucky Number 13 is most unsatisfying.
