I have ridden it twice. The first time was back in 2008 while on my honeymoon. That was when they had cast members walking around granting wishes and sprinkling pixie dust on people. My husband and I were pixie dusted rides on Astro Orbiter during Wishes. It was beautiful, but my husband and I were in the same seat and it was very crowded. Fast Forward to January of this year. My husband really wanted to ride it again, nevermind that it was incredibly cold and rainy (like ridiculously cold and rainy to the point that when my husband and I were walking from Liberty Square to Frontierland, we saw one other party because no one was there due to the weather). We decided to have our own cars this time which I found to be much more comfortable, especially since I was so freaked out and convinced I was going to fall out that I was practically lying down in the rocket grasping anything I could get my hands on for dear life. Not sure what the difference was, but I just really felt like I was going to fall out that time.
I had no issue with motion sickness, though, and I can't ride Star Tours, Tea Cups, Primeval Whirl, or Mission Space due to them making me sick, so take that for what it's worth.