I'm sure dasleben can give you all the details since he was actually based there, but the main issue is there's a lot of terrain surrounding the field. Take a look at the approach plates/ODPs.
 
Because of the climb gradients required, it makes for some interesting/complicated departure planning when one takes into account the possibility of an engine failure at various points in the climb, depending on the weather. The same can be said for arrivals. There are special procedures to follow in the event of an engine failure at various points on the approach. The company developed a "Single Engine Extraction Procedure" in the event of an engine failure while inside the FAF on the ILS, as there's no way to meet the original climb gradient required for a missed approach when flying on a single engine.
 
Plus, because of the terrain, I've heard winds can make things quite a handful at various points along the departure/arrival. Anything over 35 knots shuts the airport down as far as the company is concerned.
 
Pilots have to do ground school and annual line checks over all this stuff to be authorized to operate to or from RUT.