The Simpson is MUCH MUCH smoother than BTTF. I used to get motion sick on the old one, but that's never ever happened on the Simpsons yet, although there is one part in the beginning where I sometimes get a quick queeze. It doesn't last tho', It's a really cute, engaging ride. Ride it several times because you will notice new details each time. I love the video clip in the queue that explains what happened to Doc Brown.