Overall this scenario appears to be well suited for a large number of players who are interested in power-brokering and roleplaying. There are plenty of well-fleshed-out characters and I believe that this would be an enjoyable convention game to participate in.
House of Pain is fairly free-form. In the tradition of these games written for conventions, much of the scenario is driven by the players. This is a boon to the Keeper who can't be everywhere at once - the players know their motivations and generally try to accomplish their goals without a lot of interaction with the Keeper. However, in reading the scenario it would seem beneficial to have several NPC "plants" amongst the player base that the Keeper can use to interject information or guide the direction of the game if need be. I would prefer such a mechanic to the one suggested in the script that the Keeper guide the game by suggesting information "out of game" to the players if they get off course, or using brute force to cause the game to end in one way or another. I also worry that large-scale combat with many participants would be difficult to manage by only a single Keeper, and additional referees might be handy in this one.
My largest criticism, however, is that for the majority of the players, the game isn't really about the Mythos - I don't want to reveal too much about the plot, but if I were looking for a game heavy on the Lovecraftian genre, I would probably be disappointed. This one is definitely more adrenaline than investigation.
Finally, care should be taken in running this game, given its subject matter. Don't run this one in a place where lots of non-gaming public could be exposed to what's going on in the game. It's a sad but true statement of the times.