It's our favorite event of the year! As Mrsdoubie mentioned, there is lots of fun. If you are taking a 5yo, you might consider making sure he/she/they take a nap that day so your group can "go the distance" into the evening.
We especially like seeing characters seldom seen, the AWESOME parade, and listening to the hilarious improv interaction that goes on with guests on the Haunted Mansion front lawn.