Re: The Esoterrorists
I've run a few Fear Itself games. They might follow different parameters, since the expectation basically is for the PCs to wind up in unceremonious body-piles, but I think their rules are more or less identical.
I have mixed opinions on the system: I'm a big fan of its character creation, I'm not so positive about its investigation mechanics, and I think its general adventure mechanics are very good for horror.
On character creation, I like how Gumshoe makes players find niches among what would often be consolidated onto only a handful of stats in a generic system, and I really like the specifics Fear Itself makes players hash out for slasher/monster horror fiction.
But even after using the system for a times, I'm not really sold on its investigation system. The parts of the investigation that are really Gumshoe's schtick (finding clues without a die roll) aren't that novel, unless you've just never played an old-school or rules-light game. The currency system does work as a form of niche-protection, but it's kind of awkward and it bothered some of my players for various reasons (the major complaints were that it felt like the players were hurting their characters just to hear the plot, that it gave some metagame knowledge about the kinds of clues that could be left and that it felt like the system was railroading them into performing certain actions just to move the game along).
The complaint I had about the system from the GM's end was with its notion that the scene doesn't stop until the players grab the scene's one big clue. That's not a huge part of the mechanics, but it's tied deeply enough into the game's philosophy that I ran with it the first few times. When following that rule, when the players missed a clue but had lost interest in a particular scene, the game pretty much stopped while they ran down their skill lists looking for the last detail to buy. That really rubbed me the wrong way.
So I wound up mangling the investigation part of the game pretty hard, letting characters pick a handful of investigation skills to be "talented" at, and to find clues with as often as they like, while using a small generalized pool of investigation points to try the skills they lack talent. And I let players direct investigations, which often means missing the clues they were supposed to find. Odds are I'm missing the point of Gumshoe, but my group and I have had a better time with the modded system.
But now that I've been negative, the part I really like about Fear Itself is the system's stats-as-currency mechanic in the parts when the story gets slashy. It adds a fun and genre-appropriate attrition element to the game, where even succeeding with skills comes at a cost, and if the PCs don't find a way to safety, things will get worse for them, and the characters will be killed by skin-stealing jungle monsters.