I love Soarin', it's currently my favourite ride in WDW.
Anyway, here's a breakdown of the ride.
When you get through the ride line you walk into a room with three contraptions suspended from the ceiling (I think each section is one machine, not 100% sure though) that looks like a big JCB arm with a set of chairs on the end (No it's not yellow, I'm refering to the Hydraulic rams you can see), each one with a Wing effect on top to go with the Glider theming; and all of this sis infront of a huge concave IMAX screen.
There's 8 seats per row (I think) and in true Disney fashion, when you enter your row you move all the way to the end.
There's a seatbelt that you need to do up when you sit down, and for those smaller ones there's a loop that you can put over the belt to keep them doubly safe. You then need to do the Test Track Jiggle (Otherwise known as pulling on the little yellow tag on your seat belt to proove it's done up).
After everyone's settled, you are lifted up into the screen to a point where it's hard to see the edges (if you get a front row, I found you had to lean far forward to see the edges, further back it's a litle easier and you can see the feet of the people in front of you, go front row whenever possible). The only time I think you can tell how high you are is during "take-off" and "landing".
Then the ride starts with panoramic views of different areas (I won't describe them as it will give too much away).
To add to the immersiveness there are selective smells set off that match the scene you are watching, as well as wind blowing towards you to enhance the sense of movement (At least it felt like wind to me, I could be mistaken though). The whole contraption also moves slightly on the hydraulic rams, which coupled with the IMAX movie gives you a feeling of moveing a lot more than you really do.
After the movie ends with the big finale, it's back to earth and your done.
All this fairly simple stuff adds together to produce an awsome ride that really makes you feel you are in the action. It's definately a don't miss ride.
You've heard it already, but front row is best, and if you can do it head as close to the center as possible (Got there once myself, Concourse 1, Section B, Row 1 in the middle, it was amazing).
We went on once with people with motion sickness with no trouble, but one of our party had a fear of heights and freaked. So Motion sickness ok, heights, not so good.
After all that though, no description can tell you how good it is. Go, ride, be amazed.