I ran this for a group of 4 who ranged from (mostly) 3rd to 4th level and it beat the living crap out of them. lol They hadn't run away and outright been brutalized by so many things ever in PFS, and surprisingly they loved it! lol Maybe that says something about the people who play PFS? :P
So yeah it's a great module, but be aware it was made for 4th level's and if you have a lot of 3's it can be very tough, especially if they aren't PFS optimized. I enjoyed the story, the characters, the mix of role-playing, combat, exploration and stealth. All-in-all a very fun module and would highly recommend it!
So just ran this yesterday with a group that was a little over 5 in average level. Like most PFS games they voted to play up since in actuality most PFS games are pretty easy. Sadly for them though this was not one of those games. I really enjoyed the maps, plot, mobs and of course the end battle (although it was a b#@$$ to draw). When I compare the end battle to the laughably pathetic end battle for "Our Lady of Silver" I wonder what Paizo was thinking. Unfortunately for my group about half of them had just breezed through "Our Lady of Silver" recently so were expecting another cake walk. So all-in-all a very good scenario, I would just recommend (highly) that when you run this suggest to the players that playing up would be a very very bad idea.