I started into an ICU after nine months med-surg experience and agree with nilepoc, I had to shed a few bad habits learned on the floor.
It was several weeks before I could show up to work with dry armpits, but I had great preceptors, asked lots of questions, and, believe it or not, four months later I was second in senority with only one other nurse having been there longer than me (on nights). Doh! Talk about flying by the seat of your pants!!! It was AT LEAST a full year before I was comfortable playing the senior nurse on nightshift. When I would have to float back to my old floor, I was even a much better med-surg nurse (Med-surg nurses: I mean I was a better nurse myself, not meaning better than the med-surg nurses!) I had developed critical thinking skills, which were sorely lacking in my med-surg days.
Did my med-surg experience help? Yes, in that I learned to organize myself, develop a charting routine, get comfortable with IV sticks (we were not allowed to do this in nursing school), and also to get comfortable delegating orders to LPNs and care partners, (I always wanted to do everything myself at first because I didn't want my LPN to think I was lazy, is that silly or what?) But to be honest, ICU was where I always wanted to be and I think I would have done just as fine starting out there. I say go for it. During your orientation, you'll realize soon enough if that's where you really belong. Good luck!