I'm not the best at explaining it (my DH loves this ride and is much better at explaining but he's at work!) but this is what I think.
You go into a narrow space and there are 4 of you and you each have a job to do. There are controls in front of you and a screen that is suppose to be like you are looking out the window so you each have your own 'window'. It's a small space like being in an space craft.
You 'feel' exactly what it feels like to go into space and fly without realizing how they are doing it. It's amazing. In actuality, the pod you are in is spining in such a fast way that it makes you feel what you'd feel flying in space. Just amazing!
My advice, stare at the screen and do not look around, do not close your eyes, and if possible tense up your stomach muscles. These tips are to help you not feel sick. So far I have been fine afterwards.