I am a great fan of focus. The developers of Thunderspire Labyrinth are not.
Nowhere is this more clear than in the pantheon of evil deities that appear in the module.
Thunderspire opens with the Chamber of Eyes, an abandoned shrine to Torog, the King Who Crawls. We move to the Horned Hold, where things are run by Murkelmor, a paladin of Asmodeus. Next we go to the Well of Demons; this was originally a temple to Baphomet, demon lord of minotaurs, but the gnolls who have invaded are trying to re-dedicate it to Yeenoghu, the gnoll deity. Finally we wind up at Paldemar's Tower of Mysteries, where Thunderspire's Big Bad turns out to rather inexplicably be acting on behalf of the lich-god Vecna.
That's five separate Lords of Evil who get name-checked. Vecna actually shows up in person to officiate ceremonies during the final chapter. If we move into the bonus Dungeon Magazine encounters we find a former follower of the Raven Queen and another shrine to Torog.
What's going on here? None of this is central to the plot. These evil gods are being waved at the players for no better reason than that they can be. Torog, Asmodeus, Baphomet and Yeenoghu don't have any particular beef with the players or anyone they care about, and Vecna is so deeply un-committed to his own evil scheme as to abandon Paldemar in exchange for a few paltry secrets.
It's doubly confusing for players who've beaten Keep on the Shadowfell. "Hang on a minute," they'll say. "Weren't we fighting Orcus?" It's typically unwise to pick a fight with a second evil god before you've finished off the first one. By the end of Thunderspire players can have more epic-level adversaries than they have fingers on one hand.
This is the real problem, of course. There's no closure. There's nothing wrong with a brief tussle with Baphomet, providing that it has a conclusion. Thunderspire offers nothing - no beginning, no middle, and certainly no ending - and when it's all over you have to realise that the sole purpose of all these Elder Evils is to lend artificial significance to an otherwise deeply mundane story.