This is an excellent module with a strong eerie fairytale theme and narrative background while still being very varied in the manner of encounters, challenges and obstacles it offers players, and still avoids railroading a party into approaching the dungeon 'the right way'. I've run this module a number of times with different groups of players, some experienced OSR players, some complete newcomers to RPGs, some only having played 5e, and each group has tackled the module in a different way with a different outcome.
This is one of the best laid-out modules I've read - it is very GM-friendly. Lore is brief but sufficiently presented in bullet points, and room descriptions are clear, terse and very good at prodding the GM's imagination into gear. It's very straightforward to run with minimal prep.
This is one of my go-to modules for one shots, especially with groups unfamiliar with the OSR playstyle - it provides a bit of narrative guidance for those less used to completely open sandbox gaming, but acts as a good introduction to many old-school motifs. It's probably more forgiving than many old-school dungeons, but groups going in guns blazing won't get far. There are a good selection of encounters which encourage (and some require) a non-combat mindset.
It has some nice plot hooks beginning - each one handy for different groups, depending on where they might sit on the hero / mercenary spectrum.
For all that it has several maps, it's also quite a short module - I've seen it take between 2.5 and 4 hours, depending on the group.