One thing I liked about N was his personality in general - it was very different to that of previous villains in the series. N grew up with Pokemon, which sort of meant his activity around humans was a little awkward but he treats Pokemon as his friends.
His character development is pretty interesting for an antagonist, but it's enjoyable to look at. Especially the scene where he takes the main protagonist on Nimbasa's Ferris Wheel. It had to be one of my fave scenes in Pokemon gaming history.
He can talk to Pokemon... and he made a connection with a Legendary, which is what made him special.