I would really have to say the atmosphere kind of depends on the size of hospital and the surgical cases done there.
Coming from a level one trauma center,I find that the majority of the nurses have to be on their toes and know how to take adequate care of the patients.
When I worked on the floor I viewed the critical care staff as rude and obnoxious, but working in SICU for over a year, I find that the staff has about the same attitude as most floor nurses. Of course skills needed in SICU are a little greater, but not everyone wants to be a critical care nurse.
Hope that kind of answers the "atmosphere" part!