DFD is a module full of interesting scraps, combined into a module I can't honestly recommend to anyone. The best way to run this module is for your characters to see the mountain, think for a minute, then decide 'nah' and leave.
Is "dungeon that's not worth visiting at any level" an interesting concept for a module? Definitely, but it's one of those things that reads better than it would ever play. As-is, DFD is a great module to pillage for your own work. It's full of cool traps, chapter names like "Hell Vomits Its Filth", curses, monsters, and some amazing boss monsters. It's just a shame that the whole is worse than the sum of its parts.
...also for what it's worth, at least one of the authors on this is a thoroughly unpleasant person who doesn't deserve a cent of your money. That doesn't impact the writing, but I think it's worth knowing.
[2 of 5 Stars!]