I liked it. It was a good Marge-Bart episode. I loved seeing the families and citizens in the flashbacks, an Everyman poster on the Dungeon, and real stuff instead of parodies (Skype, 4 Seasons).
Gags I liked: Ralph being dropped on the head, the bar fight scene with the teachers, Marge's brain, Homer's books (Already Solved Crosswords, Sudoku Number Choices), "Spuckler Daycare Center, Just toss'em in the pile!", rain or shine, Sharks VS Jets, and Homer happy to see Flanders in the end.
So, 8.9/10.