I wasn't intimidated by the sensei when I started out; everyone was very kind and supportive and helpful. Falling and rolling, those scared me, but I quickly saw that the people around me were there to help.
On the other hand, I've gotten slightly more intimidated (not in a bad way) as I've developed the eye to see how good they are! I was sitting on the floor in front of Grigsby sensei while she practiced a jo taigi -- plenty far enough away for safety --and I found myself wanting to back up whenever she made a move in my direction. I am agnostic about how literally "project ki from the tip of your jo" is to be taken, but it certainly feels as though that's what's happening.
It's funny. She's never thrown me hard or hurt me, but my gut is convinced that she's Terribly Dangerous, and I have more butterflies in my stomach when she throws me than with the higher kyu-ranked students who occasionally do pound me into the ground.
In bodysurfing (the closest thing I can think of to aikido in terms of how it feels to me), when you're out beyond the zone where the waves are breaking, even a very large wave will just pick you up and put you down again quite safely. But you definitely feel that you're in the grasp of something much more powerful than yourself.