I actually rode the ride this last few weeks while on vacation in the Disney area. I'm normally not a fan of thrill rides, but I've always said I'd love to be a pilot, and if given a chance to go to space, I'd take it in a heartbeat (even knowing of the dangers that befell the Columbia crew).
Mission Space was pretty cool. Honestly, it didn't seem much different than what one feels when taking off in a plane. There was a definite experience of force on my face, with my skin seemingly drawn back, but otherwise, not that much. I felt a bit queasy from motion sickness caused by watching the image on the monitor that simulates the launch. Your body knows you are moving in a different manner than what the eyes are telling you, and I am susceptible to that a bit. Still, I didn't lose my lunch, nor did my 12 year old daughter.
Though I feel very sorry for the loss of the child for the family of the 4 year old that died, I'd have to say that a 4 year old didn't belong on Mission Space. Nor would they belong on the Test Track ride, or a few others that would be more stressful than a younger child should experience. Kids need to be told no at times, and parents need to be smart enough to recognize the warnings that are posted in the various languages. Perhaps Disney's employers were a little at fault for not providing more stern warnings to the parent about letting the child ride, but I'm like others that believes that the child that died probably had other medical problems (a heart murmur or similar) that were not well known, and they may have made him more susceptible to problems. He also could have been standing in line in strong heat, making him dehydrated, which left him more vulnerable.
Meanwhile, about a week ago, a 12 year old girl from Virginia died at a Disney water park. Not from an accidental drowning, but apparently from heat stroke. The child was asked by a park employee if she was ok, and she reportedly answered she was fine and wanted to be left alone. Shortly after, she got up, and then collapsed and died. Park employees gave CPR, but it was unsuccessful. Again, how could someone hold Disney at fault for having a child at a water park die from too much heat? The child apparently sat in the sun most of the day, barely moved, and didn't make enough effort (or her parents didn't make enough effort) to keep hydrated. Check out Orlando Sentinel's archives for news on that issue if you want more info.