Sight
His eyesight isn't particularly better but he has more eyes than most. In fact, every pore on his body is an eye and when near heat or damp, it enlarges. He can look through people's eyes and through their memories in exchange for his own.
Q: Nikolai, how does it feel when looking at memories?
A: Disgusting. When I look through people's memories, I must hold my hand out as if grabbing something and I will feel a variety of textures. *shudders* I hate it.
Smell
A little cliche I admit. His sense of smell is heightened to the point that he can feel it. When he smells snow, he will feel chilly. When he smells soup, he will feel hot. Get it?
Taste
He has two tongues. It doesn't make him taste things better though, or so he thinks.
Hearing
He can literally hear everything and nothing at the same time. Because of wind, his hearing goes stale so he wears earbuds that dull the sound. It makes it so that he can't hear anything than a few feet from him.
Touch
He cannot feel intense cold and heat.