We rode it 2x a few weeks ago. A late afternoon (daylight) ride and then a later, night time ride. Both times were great. Excellent, smooth ride. The swaying of the train cars is neat.
The night time ride added a lot, just fun to be on the train with New Fantasyland whizzing by with all the lights. Made it a bit more "thrill-ride". Don't get me wrong, the day time ride was great too. It is pretty neat to have the train slow down to go into the mine. The AA's are great! Really amazing attention to detail, so many beautiful colors (DD was pretending to gather all the gems), the lighting effects are superb.
One last tip, be sure to look very carerfully at the end of the ride at the cottage. There's some things in there (and outside there) that I missed, but DD spotted (she hasn't let me hear the end of it yet - at 5 everything is a contest for her now).
Enjoy it!
Rob