Fantastic beginner adventure with a ton of varied encounters and varied outcomes for those encounters. Plays a bit fast and loose procedurally, compared to some 'advanced' OSR content, but that's hardly a point against it in my opinion. Great, original idea with an adventure that gradually escalates from insidious strangeness to true horror.

This is a cool adventure, with a lot of content - I would guess 3-4 sessions depending on how your party goes. There are interesting locations and memorable characters, and a chance to turn your party into gibbering horrors and who doesn't like that, after all. Despite being for levels 1-3 this is no soft and fluffy adventure. Character death seems... if not probably then very possible. There is combat, there is exploration, there are a lot of NPCs, there's a horrible end, all signs of a quality adventure.

The formatting isn't what a 5e reader expects. There's no art apart from the cover, the maps are informative, but more like black and white sketches (although nicely done and electronic) and there aren't any battle maps, so ... theatre of the mind. The monsters are very cool and original - downside is that these aren't included in online encounter builders, if you use those. Also, there's no art, as I mentioned, so if you don't know what a vulgrane is (for example) you get to make it up based on the stats. There's also a lot of magic items, which also seem unique. Again, you'll have to prep if you use virtual character sheets.

So, in sum, I think this is a quality adventure but it may be difficult for some DMs to run, and I think as a DM you should carefully explain to the party that it's an OSR style of adventure in which things may definitely be too much too handle. And if you play online, you should be prepared for quite a bit of prep, or enjoy having a non-VTT game with just a dice roller!