YMMV / Baldur's Gate: Descent into Avernus

• Complete Monster: Thavius Kreeg of Elturel, after making a pact with the infernal Archduchess of Avernus Zariel, promised to condemn his entire city to Avernus to become fodder for Zariel's prosecution of the Blood War. Taking advantage of his "hero" status, Kreeg then flees Elturel to leave it to its fate while he attempts to do the same to Baldur's Gate.
• Fan-Disliked Explanation: Jander Sunstar, once a well-regarded deep cut character with a devoted fanbase from the Ravenloft campaign setting, makes a cameo in Baldur's Gate: Descent into Avernus... in Hell, crucified and tortured for eternity, having been responsible for Big Bad Zariel's damnation due to a sudden act of total cowardice as rank as it is ill-explained, then committing Suicide by Sunlight. Neither his fans nor the writer of his novels were amused with this anti-fanservice, not least because this also represents a fairly-harsh Retcon, with later books having to outright handwave this moment to fix the issue. ^Explanation He'd previously had nothing to do with Zariel, who had quite successfully damned herself eons before his time.
• Goddamned Boss: The opening encounter with the bandit captain can be this. The encounter has a few somewhat easy enemies to fight, but the bandit captain is a powerful foe for a 1st level party to deal with, and can almost one-shot the average party if not careful. It avoids being outright That One Boss because the module very heavily encourages getting help from the other patrons of the Elfsong Tavern, which allows the party to match numbers and strength, but it still is a hard fight, and can be even harder if players aren't able to get enough assistance on their end.
• Like You Would Really Do It: Getting to the end of the module presents Player Characters with several options that could drastically change the entire cosmology of the Forgotten Realms; redeeming an archdevil, determining who the new ruler of Avernus is (potentially one of the players themselves), and deciding the fate of Elturel. Baldur's Gate III would establish that Elturel was returned back to the Material Plane, Zariel was neither killed nor redeemed, and she remains in charge of Avernus, returning everything back to status quo. This carries the unfortunate realization that Lulu, having failed in her mission, would have gone insane at this outcome.
• Railroading: One of the most common criticisms of the Baldur's Gate section. While this might be something to watch out for in any pre-written adventure, the book itself states that being drafted by the Flaming Fists in Baldur's Gate is unavoidable, even saying that the captain in charge can kill player characters on the spot for refusing. Most players would have no issues doing so, but forcing the players, against their will in character, has been criticized for being too extreme. The rest of the module lacks railroading like this thankfully.
• Slow-Paced Beginning: The most common criticism of the module is how slow the first chapter is. The first chapter is supposed to get players from level one to five and help setup the story. For some reason though, the story of the first chapter feels very disconnected from the rest of the module; the Cultists of the Dead Three feel out of place and have no bearing on the plot except for the antagonist of the sections goal of weakening the Flaming Fists, the Vamthampurs are only loosely connected to the Elturel stuff, the Shield of the Hidden Lord feels like a weak inclusion due to the players having no way to do anything about it except take it along with them to Avernus if they want, and the big reveal of the Infernal Puzzle Box feels useless because the game railroads the players into not being able to open it. The only major things to take away from this section is that Thavius Kreeg is in Baldur's Gate. The difficulty of the early game also means players can often struggle to get past it, slowing it down even more. Some DM's have outright decided to skip the section entirely and just start players off at level 5 so they can jump into Avernus sooner.
• That One Boss: The Death's Head of Bhaal, who serves as the final boss of the Dead Three base under the Spa. Not only does he have just shy of 80 HP, but he can multi-attack, has +5 Str and Dex, magic resistance, a free No-Sell he can use on any damage up to three times a day, an aura around him that makes people weak to piercing damage, and he has a stun he can use that, while having a relatively low DC to make, can be used as many times as he wants. All of this is a single enemy encountered at level 2, and at the end of a relatively tough dungeon that players have to go through. He can easily kill a party even if they are careful. A good number of DM's outright suggest nerfing him because of how overpowered he is at that level, and even if the players are level 3 when they fight him, he still can practically one-hit kill anyone due to the previously mentioned abilities he has.
• That One Level: The Elturel section of the module is one of the most grueling parts of the entire module. Not only are you now in Avernus, but the amount of enemies you fight jumps considerably, ranging from lower level fiends to a few Boss in Mook Clothing encounters, all while the city is filled with hazards and people needing help. It's easy for players to get exhausted before they can arrive at their destination, which itself has several reasonably difficult encounters as well. Mind you, players are generally suggested to be around level 5 before going to Avernus, so while most parties will have gained some firepower and be moderately powerful, they still are on the weaker side, and are expected to fight multiple encounters that can be taxing.
• Too Awesome to Use: The infernal war machines are, in essence, motorcycles/buggies/TANKS in a fantasy world, with all the coolness that comes along with it. But each requires soul coins to operate, which are a limited resource at best. And a non-evil character, quite apart from the moral dilemma of using a soul as fuel, can only hold a small handful before suffering penalties to their attack rolls, ability checks and saving throws.