We've been and we love it! Starts around 7:00 I believe. THe movie schedule is posted on the CAMPING board here on DIS at the beginning of each month. Singing before with CHip and Dale coming around for pictures. You can buy smores makings at the snack stand there - always a hit.
Then the movie starts after the singing. Depending on time of year it can get COOL out after dark so plan accordingly.
THe biggest negative is the travel time if you are not staying at FW. When we stayed at POP - on teh way there it was bus to MK....boat to FW (one stop on the way)...Then internal bus to campfire area. On way home...internal bus to main bus area...bus to DTD....bus to POP. And each time you change buses - you wait for 10 minutes or so. So that's 30 minutes not counting travel time and with tired kids on the way home it was tough. Easier if you have your own vehicle but still need to transfer to internal bus to get to campground.
Even with the travel - we love it! But don't do it every time unless we have a very open night with an open morning the next day.