This is a top-tier module that would work as well as a location in a wider campaign as a one-or-two-session oneshot with minimal prep (which is how I ran it). It always does a bit extra to render a vivid picture of the setting, like how all of the city random encounters include descriptions that tie them into the established factions instead of just being stat blocks, but everything is kept succinct and easy to use at the table.

The undercity dungeon is a sort of abstract side-view that seems geared toward theater of the mind play (again, how I ran it), but the map helpfully notes room dimensions so anyone inclined to draw up a grid for encounters can do so.

The best thing I can say about it is that, a week after we finished The Well of Frogs, my players told me they wished it lasted longer. The people demand more Cassidum!