This adventure just seems to ooze fun and whimsy as I read it. All the little evocative details added to the various NPCs should be really useful to any GM running it. I definitely had to smile at "aristo-bats". One thing I don't think I saw in there, that might be fun to add, is some means for the PCs to (accidentally) shrink one or more of themselves down to rat size, or a way to increase a few of the rodents to man-size. Just for additional mayhem.