GMing Secrets of Sokol Keep
First of all, note that all the older modules are 4 hours, so make sure you have plenty of time.
A large part of the first half of this module is very heavy investigation and mystery. Some players will enjoy this, but those who want action may get a bit bored, especially if the first encounter is avoided.
The instructions for swimming to the island stretch any reasonable belief. The island is only 300 ft away (100m, so a couple of laps of a pool) -- taking 2d4+2 hours is beyond ridiculous and sounds like an error (maybe 2d4+2 minutes).
Lots of mystery on the island to investigate, so try and fit in some exposition of the plot. I find many scenarios have all sorts of wonderful background plot but no way for the characters to easily discover this. I don't like to waste this information, so try to pass out bits of the story during the scenario so the players understand what is going on.
Portraying the servants was okay for interaction, but the ghost was difficult as it had limited interaction. I literally knocked under the table (once for yes, twice for no) as the communication with the players.
The ending is a fairly straight dungeon crawl, although it also has parts they are a bit silly, e.g. creatures hiding is a small pit that you don't detect even if you fall into it.
As an example of exposition, I kept the bodies at the end separate from the undead; otherwise if you fought the bodies then the chance of deducing the plot of what happened after blasting the undead, would be impossible. As a GM, I want to tell the players the cool story that is happening.
Scaling seemed about right; I love zombies and the death save that allows the, to keep going (makes for great descriptions to players when they strike a 'killing' blow).
A solid starting scenario, but make sure your players like investigation.