What's "special" about N is that he's the first in the Pokemon games that has been able to talk to Pokemon. However, despite this fact we never really see him do it except to stalk White/Black. Sure, his background is apparently that he talked to lots of Pokemon who were abused and etc., but we never see him doing anything like that during the game.
So while it may be a cool idea, it was downplayed in the actual game.
Another thing that makes N "special" is he's a villain (of sorts) that actually captures their Legendary goal. Let's think about this for a moment.
Pokemon G/R/B/Y/FR/LG: Didn't really have a legendary goal, although they created Mewtwo... Who then apparently gave them the middle finger and left to live in a cave.
Pokemon G/S/C/HG/SS: Team Rocket was never really after a legendary in this game, all they wanted was to find their boss and then take over the world or something.
Pokemon R/S/E: (I'll go with Emerald's version of the story as it makes the most sense to me) Team Aqua/Team Magma were the first to be after a legendary (in the main series). However, they failed and wound up causing the worst natural disaster in Hoenn since whenever these Pokemon were last awake. However, somehow a 10 year old convinces another Legendary to stop the fighting and all is well. No capture here either.
Pokemon D/P/Pt: I'll admit I never did beat Platinum, but as far as I'm aware they failed to capture the legendary like in D/P. Yay 10 year olds!
(I'm not going to comment on side games, although I am aware that several dealt with legendaries such as Gale of Darkness.)
Then, finally, in B/W we have a villain that achieves his goal of having a Legendary by his side. Although his plan failed in the long run, he got the closest to his true goal out of all games. (excluding perhaps GSCHGSS, as their goal was to try and find Giovanni... which they almost did, but yay time travel!)
I like him all right, but I'm not super attached to him. I didn't really find myself growing attached to any B/W characters except White because her design is awesome.
He isn't physically attractive enough for me to develop a crush on a fictional character.
I think he's an okay character, but they should have fleshed him out more. He felt half-completed. :/ (This comes from somebody who writes ORIGINAL stories in her spare time, so she's super picky about stuff like that.)
However, when I walked into his room I just kinda stopped and was silent for a while... I probably spent at least 5 minutes in his room just going "._." at the whole thing. I honestly can't describe the feeling I had when I saw that, and that is what makes such a thing awesome.
Uh. He looks like a hippie. Unless we're talking about a different kind of "special", that doesn't make him a particularly special character.
I wouldn't call him a retard, I'd call his whole life freakin' messed up. I want to punch Ghetsis in the face (okay, maybe a little more than just that) for the whole thing.
I'd say N isn't 'special' beyond the fact he's done a few things not done in the main games before... But is overused in other media.