First of all, I can't claim to have read everything, I have seen only bits and pieces from both its anime and manga and I don't know which one is closer to the original light novel, but I'll write from what I have seen since it's still ongoing and very long. Story: 8 The plot seems to be very silly at a first point, but soon even the stupid "flushing" process gets explained, or at least thanks to Ulrike (which seems to be in the original novel and anime but doesn't appear in the manga?), plot seems to be progressing very well and gets rather serious quickly.It's a shouen-ai, what do you expect, straight men doing straight men things? Also if you're complaining about this being too gay you might try to read the first yaoi series that comes to your mind and think again, is this really that gay compared to them?

Art: 7
I can't say it is the very best art I have seen in a manga, but it's not as bad as Elfen Lied or 07-Ghost, which makes it very enjoyable.

Character: 10
I could say that simply because I find a lack of male characters in anime/manga with a multiple personality disorder. Yuuri is a teenager, and since his world is far different from the world where he's flushed in, its behavior is fairly obvious. Even though there are plenty of male characters and the only female characters have rather a comical relief, the author and the main character love to defend women's rights as seen in the later chapters, the relationships between the characters are developed very well, without needing sex scenes or references which could otherwise ruin the manga to a more straight public.

Enjoyment: 8
I'm clearly enjoying this manga a lot, it doesn't fail to alternate between humorous and serious scenes, and it focuses more on the characters' relationships rather than action, without being too cheesy or sentimental, you could define it as a perfect example of bromance.

Overall: 9
Screw the little men's reviews who want to retain their masculinity by judging this as overly gay, you can watch this even if you're straight. Once again there is no sexual content and the plot focuses more on close bromance rather than corny yaoi romance, I always wanted to read something similar to No.6 and this is the answer I was looking for.