I have mixed feeling about Change 123 manga. On one hand the story was actually interesting, on the other, there was some quite intense ecchi in it and in rather large quantities.
The story goes like this: Wimpy protagonist who is a nerd and an (Kamen Rider) otaku falls in love with his classmate Matoko who is an unpopular, clumsy, shy and antisocial girl. Motoko has a secret however, she has a split personality disorder. Besides her basic personality she harbors 3 more: the child-like Mikiri, the rebelious Hibiki and the calm and collected Fujiko. Needles to say those personalities differ a lot from Motoko and all of them kick a** at martial arts. The protagonist who, by chance, finds out Mokoto's secret, becomes her (first/only) friend (though he hoped for something more).
As I said the story is interesting, but it does have a number of flaws. At times the manga will use anything (though mostly fights) as an excuse to pull more ecchi. The thing Motoko offers to the leading guy, at the begining, to keep her split personality a secret doesn't make much sense considering her basic personality and circumstances during which she makes the offer (though he declines it). It kind of makes sense that Motoko actually falls in love with the protagonist (eventually) and his sense of justice (they make a fine nerd couple), but I can't really understand why her other personalities fall in love with him as well (and even before she did). The only explanation would be that after all, those personalities are still part of Motoko and share her feelings (possibly the subconscious ones, since the basic personality is the last one to realize her feelings towards the protagonist). Towards the end, the story starts to get silly, but there is a proper ending, so it somehow overshadows the plot holes. Another issue is the fact that the wimpy protagonist doesn't get much development during the manga (though he is slightly above the average among other wimpy shounen characters from the beginning). He gets to shine once early on in the story, but remains relatively useless afterwards. Did I mention he cries a lot?
Story wise I found Change 123 one much better than Medaka Box (aside from first 16 chapters) and Kurohime, however those two didn't have ecchi this intense (though Kurohime was rather bad in terms of ecchi). At first Zero from Kurohime might have been somewhat similar to protagonist of Change 123 protagonist, but despite being relatively weak (he wasn't really a pushover in the first place), he wasn't a wimp. What I'm trying to saying is, that the Kurohime's protagonist was a better character than Change 123 one.
The final verdict is: Change 123 was a good manga, despite all the ecchi (is that even possible?).
Speaking of Medaka Box, I said it was crap (aside from the early chapters which are good) earlier and my opinion does not change, however I have to admit that there were some awesome and\or enjoyable moments at times. For instance: Zenkichi's 40 year old loli mother welding a chainsaw.
Bonus from Change 123:
You're doing it wrong!
For those of you who've never used floppy disks let me explain: It looks like the person in the picture puts a 3 ½ inch floppy into a incompatible 5 ¼ inch drive.
Edit: Somehow I wrote FFD instead of FDD, but it is fixed now.