Contrasting view, I hate thrill rides and don't ride coasters (they make me sick!) or anything with drops, but I really love Mission Space! I won't ride Splash Mountain, Space Mountain or R'N'R, I get a little green on Big Thunder Mountain and the tiny drop in Pirates, and I was completely afraid to ride MS for a long time, but a friend talked me into doing it and I'm a convert. Loved it! Weirdly, my not-a-wuss friend (who goes skydiving!) said it was a little intense for him (a guy who thinks jumping out of a plane is *fun*!) and he felt a bit off afterwards. I think everyone reacts to the ride differently.
Basically, they strap you into a capsule thingy with a shoulder harness in front of a screen and some buttons, and you watch the screen- focusing on the movie keeps you from noticing the spinning, and it really does feel like you're flying/moving very fast- the pressure pushes you around in your seat a bit. They also blow some cool air in your face, which I found a little distracting but someone told me that it does help to keep people from feeling sick, in which case, bring on that air! I found that by following all the directions exactly, I had a good time and enjoyed the ride a lot. I found the scenery in the movie to be interesting enough to keep me distracted.
It made my stomach feel a *tiny* bit funny for a minute during the ride, and I'll admit I was very dizzy and my hands were a tad shaky after I got off, but within 10 minutes I was ready to go get another big drink of Beverly at Club Cool! (I like Beverly. I'm weird. That might mean you shouldn't take my advice).
If I can do Mission Space with a round of Beverly before and after, plus drinking halfway around the world in Epcot...maybe you'll be okay.
A more realistic checklist- can you do spinny rides like the Tilt-A-Whirl and the teacups? If you've been to Universal, can you ride Back To The Future and Spiderman? It's not so much about the motion on those, it's completely different, but the visuals on those rides can be a bit disorienting, so if that's not comfy for you, you probably won't like MS either.
As an official thrill ride chicken, I'd say if you can't do those rides, maybe Mission Space is not a good idea. If you can, go for it, you might enjoy it.