This adventure WILL run longer than the standard 4 hours. I've run three times and never once been able to get it under 6 hours. It is great fun, however, so running long isn't much of a problem, if you have the time.
While this module feels almost jarringly out of place in the season 1 storyline, it does also provide a break from the city of Phlan and its various intrigues and goings on. It may make some characters long for a return to Phlan, though, with the frustrations of a genuinely random maze, and the influences of the chaos matter.
This module also lends well to being injected into other storylines, with only minor changes to the starting point.