I felt like he was kind of freakish in a way, and when he turned good at the end I couldn't really relate to him because of that. Villains of other games were really just regular people with skewed visions, and in the end sometimes they realized their wrongs or completely changed, and you could almost relate to them in a weird way. N, however, was acting kind of freaky the entire storyline imo. I wish he had been more... normal. I can't say I hate him because he is kind of adorable.
Also I know he would battle you to see what your Pokemon were saying, but that was also kind of weird. Outside of battle, he was an extremist on Pokemon's rights, yet when it was time to battle, that suddenly didn't seem to matter a whole lot. I know Gamefreak had to have an antagonist, but still.. it doesn't really make 100% sense.
N is also kind of a weird name, kind of seems like someone smashed their head on a keyboard and used whichever letter they typed first. Why not H instead of N, because apparently his name is Harmonia? (Gamefreak kind of failed naming their BW characters, so I'm not really going to judge them specifically on N's name)
Good stuff about N imo: he wasn't stereotypically evil, which allowed him to be chosen by a legendary Pokemon, and that was pretty cool. It was different than an evil team finding a legendary and then you get to capture it. His character design is pretty cool, and if this counts, all of N's themes (when he's talking to you and different battling themes) are pretty cool. He is also kind of adorable.