These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Broken Base: Over whether or not the conclusion of Goodbye Deponia was a satisfactory end for the trilogy (see below.) It's Mass Effect 3 all over again...
Crazy Awesome: Rufus continually does things that other people tell him are impossible and/or will kill him. Despite all odds, his recklessness and arrogance lead him to victory time after time... albeit with a lot of collateral damage. It's even lampshaded in the third game, where people explicitly turn to him for a Crazy Enough to Work last-second gambit.
Ending Aversion: Many players declared the ending of Goodbye Deponia enough to make the entire trilogy up to that point almost not worth playing, if this is the conclusion it all led to.
Esoteric Happy Ending: To wit, a lot of people consider the Bittersweet Ending of the trilogy to be downright bitter. Due to some awfully contrived circumstances, Rufus supposedly falls to his death moments before finally accomplishing his life's dream of reaching Elysium. Cletus assumes his identity (thus also taking Goal back) with no one aside from possibly Goal knowing that it's not actually Rufus finally standing on Elysian soil. Elysium and Deponia are completely cut off from one another, Argus may have survived, and even if he didn't, there are still 11,000 Organon on the highboat raring to take over Elysium, which at the very least is now fated to crash into Deponia unless Cletus/"Rufus" can come up with a plan (which is implied to be unlikely due to not having the real Rufus' "spark".) The game tries to depict this as a positive thing by explicitly stating to the player that Rufus chose to fall and let Cletus assume his identity (which technically makes it a Heroic Sacrifice and supposed to represent some sort of redemption for Rufus) and that Elysium and Deponia might make it, but many players aren't buying it. Overall, things are actually worse off than the start of the installment and some fans have taken to calling it a cliffhanger for a sequel the writer doesn't intend to make.
It was worse before fans finally got the writer to concede that Rufus may have actually survived the fall and that neither outcome is actually indicated to be canon, asking the players to use their imagination to fill in the blanks. This alleviated the flack somewhat, as it allows an end that some folks initially saw as outright depressing to be seen as more of a Ray of Hope Ending and a chance for the story to go on past the games' end. Some are still holding their breath for a Deponia 4, though.
Fridge Logic: You don't think much of it at the time, but upon further reflection the whole subplot with Goaly actually being an infant Donna makes no sense. Why did she have a radically different hair colour as a baby? The purple hair apparently isn't dye, since her hair turns back to that colour when Rufus gives her the nucleic acid. And how did Donna's corpse wind up with Goal's hair colour? Hermes has no reason to change it and Argus didn't know that Rufus had been thrown back to the surface (and survived), so it couldn't be him setting a trap either.
Harsher in Hindsight: Of all things, the tutorial level. In the first two games, it was an amusing hypothetical scenario where the player learns the basics and Rufus ending up getting squished by the junk press. In the third game, however, Rufus speaks of the room as a recurring nightmare of his during the tutorial session, which still ends the same way. But, halfway through the game, Rufus ends up in this room once more, and not only can he actually be killed, this time the player sees his bloody remains. Even though he revives after death, this cycle will continue until the player can figure a way out. After doing so, it's revealed that the press is part of the cloning facility where Rufus was made, and is used to process materials to make new clones from biomass.
Inferred Holocaust: The game ends with the original problem unsolved: Elysium needs to blow up Deponia so it can get to an inhabitable planet because it wasn't designed to stay in the air indefinitely and its resources are limited, otherwise it will crash into Deponia. Only now Goal and a good portion of the supporting cast are stuck on board, and they are going to need food, and the only remaining shuttlecraft was destroyed, meaning they are all stranded. Rufus is dead, and he was probably the only one who could think up a Crazy Enough to Work plan to fix everything, leaving only Cletus, which as the game points out is not Rufus even if they are genetically identical. Plus the entire Organon is also on board, and Argus might still be alive, and there's no indication he still won't carry out his coup.
Most Annoying Sound: The cyborg dog's laughing in Chaos on Deponia is absolutely ear-bleedingly awful, and is made worse by the fact that you hear it with pretty much every interaction with the creature (so expect to hear it A LOT thanks to Trial-and-Error Gameplay). Seems to have been done on purpose, as it's one of the only voice clips in the game that cannot be skipped.
Painful Rhyme: Every one of the narrator's intro songs is a stumbling mess of lyrics. The page quote is one of the few times he rhymes.
The Woobie: Poor Bozo. He gets dragged into problems by Rufus, who makes fun of him all the time, calls him a pirate despite his insistence otherwise, makes free use of his ship, destroys his things, and eventually destroys his ship. And Bozo is too nice to do anything about it. Plus his girlfriend is violent and his family are kind of jerks.