I second B4 myself.
Great module, lots of roleplaying, and can be expanded into a mini campaign.
In particular, however, this module has loads of room for improvement (though it was a great module, don't get me wrong). I just thought this module was a great example of the limits of Basic D&D's alignment system (A religion complsted of neutral female fighters, versus a religion composed of lawful fighters, dwarves, and halflings!!). Plus, they could provide further detail on the lost city and other areas not covered in the module.