I ran this last night in high tier, and my group had a lot of fun. To start with, it was enjoyable for me to role play the various off-color NPCs. How often do you get a city of traditionally vile humanoids as the back drop for your scenario? They loved that the city felt unique with the festering river and colorful NPCs.
I had small naked, Orc children try to run scams on them for coppers and silvers, only to kick them in the shins and put their clothes back on when they got waved off. This made most of the PCs smile. They were all convinced that the source of information in
was out to get them with his "wares" considering where they thought he got the potables from.
The predictable fight with the expected monster was made unique by the compelling interest given them by the
and that just totally overwhelmed their benefactor.
Thanks to clever playing and RP,
they worked their way around the final encounter without the expected fight and managed to impress the NPCs as well as earning quite a name for themselves.
If we hadn't been pressed for time, they would have captured the optional encounter as well and probably could have taken over Urglin, if they had so desired.
All in all, they never felt like there was a rail road (each experience feels different depending on how well the GM hides the tracks, I suppose), went to the different districts as they pleased and deduced they'd have better luck
and figured things out without any prodding.
Given a GM who is willing to have his NPCs act gruff, surly, sour or just plain difficult until given a reason to be helpful (especially when nice to half-orc PCs), the players can have a great time with a scenario that doesn't involve "murdering everyone for being evil."
I'd say the main limitation is that for those wanting lots of combat, much of it can be avoided (Charm Person/Monster, Deep Slumber, etc). The essential fight was brutal though. Characters playing up or unlucky can get eviscerated by the foe. The Pre-gen Kyra got to save the day with her Channel Energy.