It's really cool. This year they added Sally, and she stands in the graveyard, leaning on a tombstone, wistfully looking at Jack. I love it. Also, they hide the "monkey bride" in the attic each year. They dress up the clapper monkey, and each year it's in a different place. I looked for it twice and missed it. My daughter found it, though, on her first ride. It's dark in there so she's usually hard to find.
The first two pics had flashes, the last one is typically what we see.
Haunted Mansion is my favorite attraction so I was dubious when I found out my first visit to the DL version would have this overlay. I loved it, though! Something about the color palette and alternate storyline really appealed to me. I've since seen the original version there as well, and I'm glad they have both.