And now, the rest of the story...
We were at MK and TennVolTony called me about 3:00. He told us we should high-tail it over to Epcot because there had been guest previews of M:S the day before at 4:00. We got out as quick as we could and hopped on the monorail.
As we passed through Epcot on the monorail, we could see that the wall of trees that had blocked entrance to the M:S building during previous days had been removed and the only thing blocking entrance to the building was a wall about four feet high. We entered Epcot and headed straight for M:S. There were about ten people standing around the wall when we got there and we quickly learned that they had the same information that we did. We could see several cast members in uniforms and LOTS of managers milling around the entrance. We could also see the video monitors going and hear the music and sound. All very good signs...
We waited for about 20 minutes and at 4:00, several managers came out and one of them asked us if we were waiting for anything particular (with a big grin on his face!) He said it was our lucky day and opened the gate. By this time the group of guests had grown to about 50 and we all followed the managers into the building and through the queue. They walked very slowly and we marveled at the detail of the queue area. My wife took pictures (she didn't even have to be sneaky

).
The preshow consists of Gary Sinise and an unknown (to me anyway) actress describing what our mission would consist of. On several occasions during the preshow, the chance to opt out was given. Guests were divided into groups of four and each member of the group has a different job in the mission. Gary described each job and acted as the voice of mission control during the ride.
We were ushered into our pods which have four seats each. I was the navigator, my wife was the pilot, and two other guest were the engineer and commander. At a particular point in the mission, each member has to press a button on command.
The pods are a bit tight so if you're claustrophobic, you might want to pass on this attraction. They have over the shoulder harnesses.
After we were strapped in, the pod rotated us so that we were on our backs looking up at the sky and the top of the launch tower. The blast off was amazing! You can actually feel your face flatten out from the G's! You leave earth's atmosphere and head toward the moon. You fire your rockets while over the moon's surface and slingshot around it to head for Mars. There is another good dose of G's as you slingshot around the moon and then you are put into "hypersleep" until you arrive at Mars. Something has gone wrong (surprise, surprise) and you have to help steer the ship to a rather bumpy landing on the surface.
This is just a basic description, partly because I don't want to completely spoil the surprise and partly because it's unlike any attraction I've ever experienced.
The post show area is very good and has several interactive displays and games. As usual, you end up in a store (where we promptly bought $50.00 worth of tshirts and pins). There were many managers there and we were asked several times if we felt sick. We didn't, but I understand several people did.
We're going back tomorrow with TennVolTony to see if we can ride again. I have a feeling they're going to do this every day this week so we're going to take advantage of it while we can.
This attraction is going to be very popular. It's Disney through and through and the themeing is unbelievable! As you can tell from my username, I loved Horizons and have been waiting to see if M:S is a suitable substitue. I have to say that it definately is and far exceeded my expectations.
That's all for now, I'm full of pork chops from Big River and need some sleep!