Bazel is pretty right on.
It's definitely multi-generational in its draw. Even kids would get bored with it after a few songs. Luckily, they have video games. I'm no old fogey, but I do appreciate the organ music. I'm funny like that in that I can sit for a long time and get lost in it all because it reminds me of my grandparents, and I miss them.
It's been a long time but this is what I remember. Good, basic pizza (no frills). Picnic style tables lined up end to end and a REALLY LOUD Organ. That being said I think the draw is firstly the music then the food. I think the Organ Stop can be a great family or multi generational family destination.