I got this game for 99 cents. For that price, I would definitely recommend it. At a much higher price, I wouldn't. But I don't want to base my recommendation on price, and since I wouldn't play the sequels even for free, I'm gonna go with "not recommended".
If you like humorous 2D point-and-click adventures, Deponia might be for you. It combines a fresh setting with "industry"-standard storytelling and mechanics. I liked the artwork a lot and the protagonist, Rufus, is quite enjoyable.
There are a lot of things I didn't like, however. First off, it aims for the classics, but the writing is not remotely as good (with a some exceptions). A few times the humour is so forced that I couldn't help but feel remote shame, as in "did they really think anyone would find this funny?"
Most of the quests and puzzles are straight-forward. But some of the puzzles are just aggravating. We've all been there, trying anything with everything in the inventory, to no avail. Or clicking different levers to see the desired effect. But some stuff in Deponia is just completely non-sensical and drove me mad. I admit I had to look into a walkthrough a few times, and mentally flipped the finger towards the developers a few times once I'd found out how something was supposed to work.
From a technical perspective, there are 2 things I found wildly inappropriate for a 2012 title, especially if it's published at (almost) full price: #1, the animations. You will see a lot of generic "empty hand movements" when you do stuff with things. I found this particularly disappointing given how much love went into the artwork otherwise. #2, lots of interactions will just yield the same line over and over again. For instance, when you are trying one specific item in your inventory with every other item, you'll hear the same crappy joke over and over again. Very tiring.
Overall, I would say Deponia shows lots of promise, but some aspects are just disappointing and frustrating.