They weren't very big. Maybe a little smaller than the moon jellies at the Toronto Zoo. All of the jellyfish species (I think there were 3) had their own tanks. My favourite part of Planet Jellies was one section where it showed live moon jellies in each stage of their life cycle. Other than that this section was pretty boring, but at least the animals look cool.
Well you summed up jellyfish pretty accurately. Boring but cool to look at. They are are peaceful to watch. I like the Planet Jellies because they have some nice colouring that adds to their appeal.