I've GMed over 100 PFS sessions, but rarely have I been compelled to write a review as much as after GMing Mantis' Prey - this is my first public review of any Paizo product ever. A few things stood out to make this an awesome experience for my players and I:
1) Awe Inspiring Location!
Print out the map in 1" battlegrid full-colour if you can, rather than drawing it by hand on a battlemat, as it really is awe inpiring to be battling behind a raging waterfall!
2) Puzzles you can solve!
Puzzles that players can actually solve on their own without resorting to skill checks - though those are available too, if you need them, but it really diminishes from the sense of discovery and achievement (not to mention fun!) if you do.
3) Red Mantis + GMT = Wow!
The Red Mantis - everyone who's heard of them, fears them! This is the first time I've ran a session with them, so it was fun to learn who they are and what they're capable of. Full of menacing flavour, they didn't disappoint.
Michael Kortes wrote the original Silent Tide wherein you first meet the GMT easing the pain of unhealable burns in his bath, surrounded by an entourage of half-orc bruisers, doing business deals and opening strange chests, who doesn't love the GMT?
Well, in Mantis' Prey, you meet GMT again, and he's in splendid form! I've often felt that multi-part scenarios written by different authors lack cohesiveness. So in this regard, I'm glad Michael Kortes was tasked to revisit GMT himself, because all of his signature elements are here!
YMMV) A Smorgasboard of Feats/Abilities
If I were asked to identify a minor annoyance, it would be having to reference three hardcover books to run the Red Mantis = Core Rulebook + Advanced Players Guide + Inner Sea World Guide. It's often difficult enough finding time to read the scenario during a working week before a game, I do this on the brief train commute to/from work, so looking feats and class abilities up across separate sourcebooks before a game often gets overlooked. As more sourcebooks are released, this is something we'll need to get used to. It's not a huge complaint, and shouldn't affect your decision to run this scenario - if you're running Tier 7-11 scenarios, there's a good chance you have these products already, but if not, ignore the asterisked* feats/abilities and the scenario runs just fine without them.
Pathfinder Society 4-Star GM