WAY to long for a 4 hour slot, the first half of the scenario HEAVILY favors skill monkey PCs (again), "gotcha" unexplained traps and mechanics, and a tacked on final fight. I cannot recommend this scenario, especially to any group that has less than 5 hours.
And WAY to long. It took our experienced group almost 12 hours to complete this mod, and we skipped or hand waved several (4?)encounters along the way. How is someone supposed to GM this at a Con or event with that kind of run time!?!
The first part of the mod was good, until we reached the island. Then it felt like we were getting repeatedly hosed for no good reason. The hourly mutation chance, with no ability to stop or even understand it, made us feel like we certainly had no time to stop and rest. And we really could have used some rest.
A encounter with a CR equal to the APL of the party is supposed to consume 1/4 of the party's resources. On the island we had way more than 4 encounters (6-8, and we skipped some)and one of them was CR=APL+3, all before reaching the climactic encounter! How is a party that has no time to rest supposed to have anything left for the BBEG after that?
If we had had a Sorcerer instead of a Wizard there is no way we could have made that DC40 Spellcraft check, and with out it we would have been screwed. And what is with requiring 4 ranks of Spellcraft to assist the check. Did someone pull that number out of the air, or was there a reason for it? It certainly doesn't seem fair to be changing the rules in a PFS module.
Finally, the extensive use of permanent illusions felt cheap, especially the final illusionary wall. When "it" popped through I wanted to just leave the table in disgust and frustration.
This is the first time I have been actively pissed off after completing a PF module. Not with our GM (who is great and did what he could to not make this mod last 14 hours), or my party members (a stalwart bunch), but with the adventure itself!