As far as a prewritten adventure goes, this was a pretty good one.
The encounters are extremely well written and there is enough information to easily pad it out to last longer than four hours if you have the time for it. It seems well balanced, and again is easily modified for veteran groups.
On the flop side, the plot was extremely transparent. Our GM ran it for me and within twenty minutes I had figured out the main "twist" to the module.
It is also a very good read just for the background information if you are wanting to run the Orc Underground campaign apart from missions.
[4 of 5 Stars!]