I just got back from a long weekend as well, and the ride is certainly worth the wait! It uses the same technology from BTTF - but it seems like it rides much smoother. I don't know if they've improved the technology, or if it is just because they had stopped doing any sort of repairs on BTTF long before they closed it.
I'll try not to spoil anything: You're visiting Krustyland, and Krusty explains that Sideshow Bob has escaped from prison and wants to kill the Simpsons, and anyone else who gets in his way. While waiting to be the first to ride the new ride, Krusty picks the Simpsons and lets Bart pick one other group - he picks the folks in the waiting room, and off we go.
You start off on a roller coaster at Krustyland, and then mayhem ensues. The ride film is excellent, and there are tons of jokes. We rode it twice and picked up on a ton of stuff that we missed the first time.
The queue has a whole bunch of flat screen displays, and the pre-show video runs over 30 min before it repeats itself - we timed it. The pre-show is a mix of classic Simpsons clips - mostly dealing with theme parks. They hit Disney hard, including the Duff Gardens version of it's a small world where the children of the world are drinking Duff beer.
It is interesting to note that all the characters are there except the ones voiced by Harry Shearer.
As for motion sickness - you might want to be careful. They have you riding on twisting, turning out of control thrill rides more than once.
We really enjoyed it.