BEST in capitals, because this scenario really deserves it. This scenarios breaks from the predictable "encounter-encounter-encounter-encounter-endgame" routine of many PFS modules, and goes for something a little different. It is quite challenging, but in the best of ways.
In order to succeed in this scenario, players must work together, and characters must work together. There is a clock, and it actually is ticking. Players better be ready to ROLE play - there will be plenty of opportunity to try for that monster critical, but if that is your primary concern then you might miss something along the way. Likewise, faction missions can (and maybe should) take a backseat in this module, because time is not on the characters' side.
Make no mistake, this is one tough scenario. But rather than seeing it as a player (penalty to character if losing the mission, possibility of not getting faction award, etc.), consider this from the Organized Play Campaign and a character in the world side of things... not every Pathfinder is going to succeed in every mission they undertake. For some, there are consequences. From the role-playing side of things, this is one mission where I hope they pick up the discussed thread of there being "real world" game changes based on how factions - and the Society as a whole - perform in specific scenarios. I for one welcome a module that we can't ace with our eyes closed - I want to work for my rewards, and want to be drawn into the world!
That said, I will admit that this mod is a rogue's paradise. With so many combat-heavy modules, the skills and the chase mechanic used in this were an awesome change that I (playing a rogue) enjoyed very, very well.
All in all, this mod is excellent, and a very welcomed change of pace!