We rode Mission Space in January, and have a couple of observations. I only went once, but I would definitely go again.
Yes, it is a centrifuge. So, if you have a head cold, like I did, you should expect to feel weird.

I felt "off" for several hours after the ride, but I'm sure it was because I was stuffy.
Then there's the sort of self-fulfilling prophecy with this ride. About 9,000 times before you get to the capsule thing, you're told that you "could" get sick.
So, the kid (she was maybe 7) sitting next to me in the ride spent the entire ride telling her father she "felt sick." I don't know if kids know the difference between feeling "sick" and feeling "weird" LOL. (I also didn't appreciate him switching places with her so that she sat next to me. What if she HAD become sick? UGH.

) It would have been better if she hadn't said "I feel sick" every 10 seconds during the ride. I think she was convincing me that "I" was getting sick.
The sensation is very cool. Disney won't say what the "G" force is, but I read that it is about 2Gs. (Regular gravity is 1G.)
When you ride, pay attention to how "hard" (not hard, but different) it is to move you hand to the controls that you are to push. That's REALLY cool.
I liked it, but couldn't believe how boring the area to queue is. Dull, dull, dull. They need to show some space film in there or something.