This is a dungeon that knows it's a dungeon. It doesn't try to "theme" its inhabitants very much (although individual "factions" have their own cohesion), instead justifying their coexistence with an origin that is effectively the big brother of "a wizard did it". For all that though, there is a decent amount of narrative. While most encounters are just obstacles to moving around, many are memorable and well-done, and the three Splinters with the keys are a nice progress tracker. Vyrellis is another nice call to the story. Using the "killing splinters returns power" to excuse the big K himself not showing up earlier feels like a bit of a wheeze to me honestly, and the time pressure that it supposedly imposes is a bit of a joke, and the keys riddle is brute-forceable which is unfortunate. The final battle here, though, has a nice wacky mechanic that fits this king of prisoners.

Good on its own, but don't expect too much plot tie-in to the rest of your campaign -- the hooks to the suggested preceding and following adventures are weak as are most in the 4e HPE series, but I'm not sure there is a much better way to tie it in to anything. You could place some MacGuffin in the Pyramid, but ultimately it's designed as a self-contained dungeon, not a part of a broader story.