I would hazard around 90 minutes because more than one poster has stated reservation times of 5:30pm and 7:30pm and they need time to get everyone out, clean up and setup for the next group.
I think this is hard question to ask general public since people have different values for experiences and food.
I would say if you would put down the dollars for CT Lumiere or the new WMD, then 360 is more or less in that price bracket. If you avoid those and just do SD (e.g. Crown Grill or Sabi's), then perhaps you wouldn't see the value. Of course, curiosity can often win the day.