My players finished the romp through the Cinder Throne, so I can share that this was the map that I was using without it being a spoiler per se. I really loved a few things about this dungeon and how it turned out.
Last night's group was as different as could be from the previous delve. Before there had been a fighter, an elf and two thieves. This time there were two fighters, a dwarf, two clerics and two elves, including the fighter and elf from the last session. It helped that the first fighter and the dwarf were level 3 and the other fighter had been sitting right below level 3 from a previous adventure. The troglodytes that had seemed like a bad idea the previous time were pretty readily dealt with this time. A random encounter with a party of Veterans turned into some harmless parlaying; the fact that it happened as they were leaving the troglodyte room and most of the fighters got sick from the stench helped with that.
The dwarf PC's hardiness proved itself when a giant black widow spider got the jump on the party; it bit him but dwarves are great at saving versus poison. The party was able to set fire to the webs and do some damage to the other spider hiding in the web-filled room, and take it out before it could do more damage. The Moldvay rules really encourage setting stuff on fire, and particularly spiderwebs if you read the description of the Web spell – the black widow spider webs are explicitly like the spell. I guess the logical deterrent would be to have something valuable like a scroll, or a human voice crying out from the spiderweb; otherwise a room full of webs is an invitation to set fire.
I had put an arrow trap in the angled hall with a niche toward the center of the map. The PCs used a 10-foot pole to prod the niche and trigger all the arrows, and the elves found the secret hole in the wall with some gold; if they hadn't prodded ahead, there was a second pressure plate in front of the gold that would've fired arrows. This carefulness went to the wind with the dead end a bit further on, where one of the elves promptly fell into a pit trap. There's just something about pit traps that gets 'em every time.
Then, because variety is the spice of life, I threw in some OD&D gnolls. Not that they're mechanically any different from Moldvay gnolls, which fit the hyena-man variety, but the vibe was a little non-standard when I was doing the dungeon stocking and I enjoy simple reskins like this. One of the elves wisely used a Sleep as the gnolls had spent their surprise round throwing axes at the PCs, so that was ended rather quickly. It wound up with one of the long-suffering fighters getting a Sword +2, so that was worth it.
(As a side note: while people buying modules often complain about generic loot like weapons with pluses, in play I've always found players quite happy with them. A Sword +2 is nothing to sneeze at, even if it doesn't have a particular backstory or weird power.)
After the gnolls they managed to get pretty much straight on to the area at the bottom of the map, going down into the room at the base, which had a weird pillar that would sometimes tell the truth and sometimes lie (by random roll). I can't remember which particular random generator I pulled this one from, but it worked and the PCs used questioning to figure out which room had the crown they were seeking. So they went to that room and saw the crown.
Now, I should mention that the dungeon walls bore scorch marks, pretty much throughout, as an atmospheric thing. I placed the crown in the one room with no scorch marks, and that single detail freaked the players out. They wound up dragging a heavy chest via rope, to make sure it was not trapped, and then checking almost every element of the room for traps. Except for the ceiling.
So when they finally made the plan for the elves to grab the crown and run, with everyone else already cleared out of the dungeon, the gray ooze lurking on the ceiling made short work of the elves. The red herring of some horrible fire trap had gotten the players to carefully check every aspect of the room except the one that had the actual danger, including performing a Detect Magic.
The other PCs came back and managed to get the crown, which was worth 5000 GP, and rightly was the crux of the adventure. Gray oozes are very slow and this one was already "feeding", so it ended well for the more established fighters and clerics. It's fascinating for me when plans go like that; I had decided in advance that only specific inspection of the ceiling would give hints to the ooze and the players didn't check it. If they had, they would have had to deal with the ooze otherwise.
I can't over-emphasize how happy I was with Dyson's map. The three-dimensional elements and hidden chutes were really quite neat and added a dynamic to the adventure that I enjoyed very much. I played with the "S" circles being like manhole covers that the players lifted to get to the chutes below.
I stocked it using Moldvay's dungeon stocking rules, which usually lead to a pretty interesting time, and used various substitutions as I saw appropriate. One thing I've been careful to do is add 1d10-5 to anything with tens of coins, or 1d100-50 to anything with hundreds, which results in coin amounts that don't feel arbitrary. (I never give exact totals until the PCs are out of the dungeon, of course.) I have generally replaced about half of the "typical" encounter types with unusual and bizarre things; it creates a memorable impression without being too much in weird-land.
So the game goes on, and the next adventure I might have a couple options available for the players to pick a direction. Overall Moldvay works really well in practice, even if it has a few pyromaniacal tendencies.