So far the nicest hostel i stayed in in Scandinavia. Though that also shows in the price - i would also expect more for ~45€ a night instead of 17€ ;)
But its very nice, very clean, the staff is super friendly and helpful and they have a great and clean community kitchen!
Only thing is, that i feel you have to walk to the city center. Its only about 20 mins but up/down quite a steep hill so thats a bit hard with luggage. Might just be my fault though, the pubkic transport in Trondheim is very confusing to me.