well, this is certainly going to be a fun review to write...
put simply, this is an adult retail store. if you don't like reading about this sort of 'stuff', then stop here!
castle is a HUGE sex/party store. it's a warehouse with a giant section of porn videos, lots of exotic clothing, body lotions, adult games, books, novelty items, and one entire wall devoted to, um, electronic devices, mostly oblong-shaped :-)
it's a fun and funny place, brightly lit, does not feel seedy, and the perfect place to visit if you are heading to a bachelorette party, etc.