The seats are just seats, with lap belts. It's as though you are passengers in a small space cruiser, and you are looking forward at the pilot and out the front window of the spaceship.
It's a motion simulator, so it dips and banks turns, it shakes, it's FUN. IMO. And I want SO much to know how they make the feelings so real, b/c even when I close my eyes (to check if the feelings of, say, falling, or accelerating, are just created with an optical illusion) I can still feel those motions. Oh to work behind the scenes for just a day on those "vehicles"!
I first went on ST during a visit where I was dealing with a MASSIVE FEAR of coasters (after two years of re-discovering my LOVE of coasters). I blame being put in the front seat of Space Mountain; I couldn't get my fear-brain to shut the heck up, and it ruined the coasters for me that trip. Last, or second to the last, day of our trip I went on ST and fell madly in love. The feeling of the coaster without the "danger"! Lovely!