This particular scenario is a very dark and disturbing one. As noted elsewhere, it is very much in the "purist" vein, though there is a brief section at the end that describes how to "pulp" it up and add more action in. Basically it is a one-night episode, not really suitable for staging as part of a campaign. It could, however, be used effectively as an interlude in an on-going campaign, though the players will need to work out their motivation for going to the Island.
The scenario is designed to invoke the slow build up of creepiness leading eventually to a classic Lovecraftian denoument wherein the investigators learn that even their best efforts may be useless in the face of the mythos. There is no combat in the scenario, so if your group enjoys fisticuffs and gunplay, they may be very disappointed by this particular adventure -- though maybe that would be a good thing for some groups. There are plenty of role-playing suggestions for the Keeper, which, in my opinion is a much underutilized device by most scenario authors. We could always use more suggestions on how to role-play the walk-ons and bit players.
As usual, DriveThru has done an exemplary job of reproducing the book. Overall, given that it's a bit grim, I rate it a solid "4."
[4 of 5 Stars!]