Ah, Nodame Cantabile. I'm a big fan of yours. The anime really got me hooked up-- from the first season, second, til the finale. It was really breathtaking. So I tried to give the manga a chance.

Story: 10
I'm not gonna talk about the story though, it's completely stunning, because the manga and the anime is just the same. The story is unbelievably realistic, and as the story goes on, it doesn't forget about the main topic, which is music. To me, this is undeniably the best music-themed series ever. The story doesn't lack of musical knowledge, instead we're offered so many musics, in this case, classical music. It doesn't suck at delivering the main point and we got to enjoy the story quickly. Way to go.

Art: 6
As for the art... I don't know whether it's just me or it looks kinda unstable. Sometimes they look so beautiful but sometimes they look kinda funny (lol). Well... I personally don't really like the art. See, it's like, so simple compared to all other mangas I've ever read. It doesn't show much of details, and it's not very neat either.

Character: 10
The character relates to the story. So we have two main characters: the perfectionist Chiaki Shinichi and your genius Noda Megumi. Their character isn't something particularly new: a harsh guy meets an eccentric girl, the girl falls in love with the harsh guy, the harsh guy rejects, the girl stays persistent, the guy realizes the girl's pure feelings and he started to open his heart. This could sound really boring because this plot has been used for over than thousands series out there, but ChiakixNodame pairing didn't disappoint me. Well, at the beginning I was kinda disturbed because their relationship doesn't show any improvement, but I'm happy they didn't let me down. Their pairing is so, dunno, fresh, because there is also something that shocks us and prevents us from getting bored. And besides, their characters are also strong and are understandable by the readers.
Then... aside from the two main characters, the other supporting charas also did their job well. We could... feel their presence, and their existence becomes more important to us as the story goes by, even though they're not the main players.

Enjoyment: 8
I would like to give 10 if we could hear the music as we read the manga... but unfortunately we can't. Yes, that's the only weak point of this manga. This manga is about music, and if we dunno the music that is being played (sometimes Ninomiya uses uncommon classical musics, am I right), we can barely imagine the feeling. The situation. Well, the good thing is that only weakness means nothing in the anime. If you're kinda disturbed by not being able to 'hear', I suggest you to watch the anime. Now.

Overall: 8
Aside from the flaws such as the unstable art and the silent music, this manga is pretty enjoyable. Well, the story itself is fabulous indeed. At least you could imagine the music being played, haha. Even though I highly recommend the anime series more than this manga, since you can enjoy it to the fullest.