Mini solo dungeons are difficult to pull off. You have a limited number of paragraphs to play with and it's easy for it to become too railroady. Andy Holmes' The Halls of the Gorgon succeeds for the most part, offering a winding dungeon full of passageways in only 60 paragraphs. However there are a couple of technical flaws and a lack of memorable monsters that hold this solo back from being a classic.
The solo is set in an ancient Dwarf mine called Ogul-Duhr, which has become the home to the more sinister things of the world, namely a Gorgon (I.e. Medusa). If you're unlucky you could face the Gorgon before you even enter the mine. The dungeon itself is mostly a series of winding potholes separated by caverns. Most of the random encounters in Halls take place in these narrow corridors. There are plenty of options in where you want to go, so you better draw a map. The larger cavern areas are generally devoid of much, except maybe a bridge, and there are few set enemies, so you'll be rolling on the encounter table a lot. The creatures themselves are mostly natural, such as beetles, snakes, spiders and centipedes. You will rarely come across a humanoid in the adventure.
The Gorgon herself is the star of the show. She stalks the dungeon and can spring up unexpectedly. Holmes has done a great job in giving the illusion that the Gorgon is slithering around everywhere, forcing you to constantly be on your guard. Actually bumping into her as you explore is a good thing, as she isn't at full power. That's not to say she isn't deadly. She's not strong herself, but uses a 5d6 magic sword, can turn you to stone if you fail a luck roll you take every round, and she can knock you over with her tail to get a free attack against you. Really you have to have a strong, lucky and fast warrior to defeat her. If you face her in her chamber then you have a very slim chance of killing her. Trust me.
One niggle I had with Halls was that some paragraphs required you to go back to previous one without warning. If you don't keep track of your paragraphs then it can be annoying to flick through the book to find the right one. Fortunately it's a small solo do this isn't a big problem. There is also a broken paragraph that will leave you reliving the same challenge over and over.
Halls is lonely and claustrophobic, which is how it should be. It feels like Alien and you're trying to kill it before it gets the jump on you. It says no more than 20 adds should be used, but that could make it very hard indeed. Holmes is a great writer and Halls is a solid solo, even with it's flaws.