Disaster opened for Technical Previews today, and I went to it. All in all a big thumbs up. The ride portion hasn't changed much, but the pre-show is actually pretty fun (and amazing in places, especially the second room and the "pepper's ghost" like effect).
It may or may not be open for more previews during the week, it's still set for a grand opening next week.
Overall it surprised me in a good way. Nearly everyone was laughing on the ride back to the subway station from the monitors that are now in the trains.