I've only been twice—this year and last year. My son and I loved it! Our favorite things were the characters on the treat trails, the parade, Villian's Grove, low wait times for rides, and checking out everyone's great costumes. My 9-year-old son LOVED the trick or treating and it was his main focus during the party.
The only thing I hated was it is too short. I wish the party started at 5pm rather than 6pm. Or went to midnight (though that would be a stretch for my son). The time FLEW by both times we went.