Suffice it to say if Aquaria was released during the SNES days it would definitely be considered one of the greats of its time.
Dust though is more of a technical demo disguised as a game.
Technical demo for what? The group that made it or the Microsoft game-creator-thing program?
Finished Dust. It's certainly not Aquaria, but that's not saying that it's bad. The backgrounds are very artistically appealing, and I felt like it worked very well. The hack-and-slash action was pretty fun, and the controls, even on a keyboard, felt solid. The only exception to that is menu browsing, which I'd either use my mouse for (which I did), or a controller (which I don't own). Dust, his sword, and the sidekick Fidget were all well-executed artistically, in my opinion. However, I felt that the art for the rest of the characters was not that good, but I'm not sure what else I could ask for. Perhaps it's that all the people are anthropomorphic animals instead of people that threw me off, but it just didn't feel right. There are also a few moments where the character animations during dialogue felt like gratuitous 3D modelling.
The story was pretty good, in my opinion, but I think it could have been improved with a bit more internal conflict for some of the characters (not going to explain, because spoilers). They definitely surprised me with a couple events that unfold that 'hit me right in the feels', so to speak. The voice acting was also pretty good: sometimes it was spot-on and well-executed and other times it could have done better. The ending, though, that was really well done. Boss fights throughout the game felt very "meh", but they pulled out the stops on the last one and it did feel appropriate as a final battle. That ending cinematic, too. Man, that ending cinematic. That was well beyond par.
So, Dust: An Elysian Tail has great scenery, really good art on average, and a pretty good story. This would be wonderful for an immersing experience, but Dust's greatest weakness is that it never stops reminding you that it's a game. Right from the beginning, you get the whole "To quickly attack with the Blade of Mal'jahsed, wielded once by Lord Aerlon, Son of the Bloodied King, forged in the fires of Strathelm at the Core of the World, press the 'B' button" bit (not an actual quote). The sidekick also repeatedly breaks the fourth wall. This wouldn't be that big of an issue if the game felt more like a parody, and in some cases it does feel like the game itself isn't taking it too seriously, but with a story so compelling and a world as beautifully detailed that just begs to be immersed in, it just feels wrong, like it's pulling the player in two separate directions.
Aquaria also had a very neat and personal story and an absolutely gorgeous world, but it didn't kick you in the face every time you leaned in too close to what was happening. Playing Aquaria was like living Aquaria. Playing Dust is like playing Dust and wishing you got to be on better terms with it.
Is Dust worth $14 or $15 bucks? I think so, but mostly because I think that charging less for a solid game that's recently come out isn't a good idea. I can't honestly say that I'm perfectly satisfied, though. I think that the next game put out from the same developers has the chance to be great, but it feels like Dust missed its mark for me. I'm certainly not saying that you shouldn't buy it, though. If you think you'd probably enjoy it, you probably will. If you don't think you would enjoy it, then chances are you probably won't although it may surprise you.