it is surprising to see the variety of restaurant here in this small town Longyearbyen - western, japanese, thai - but you can try all these somewhere else in the world. if you want to try something special in this special town you may visit vinterhagen.
Beside some "normal" dishes like beefsteak or fish, you can try whale or seal steak. i cannot say the taste was good or bad, but it was special.
It is a 10-15mins walk from the main street. May be it is the reason why there were only a few guests at the time of my visit, while the other restaurants serving ordinary dishes were all fully booked.