Let me summarise what I've seen so far and maybe that will help you decide whether to buy this game for 20 dollars or not.
First of all, if you are a fan of Quest for Glory series, you WILL enjoy this game - it has that same feeling to it. The art style does a great job at attempting to stay true to the classics and the music (at least for me) fits in the game perfectly. Regarding animations, this game succeeds with them and even the gory parts of the game have turned out good. As for the voice-acting, in general they've done a decent job with it and there are very minor flaws which probably won't even bother you. I've only encountered one monster but the fighting system is very simple and easy to learn (basically it's like in QfG, you hack, slash, stab or something of the sort). And last but not least, the game has a good amount of humour which you will witness here and there.
So in conclusion, aside from very small details regarding voice-acting, I would call this a perfect game. I understand 20 dollars is expensive for some people, but think of it this way - it's thrice or more times cheaper than your usual triple-A title on launch, so I would take it as a bargain if I were in your shoes, deciding. :)
EDIT: Alright, I've completed the game and I have to say that this game is TOTALLY worth the 20 dollars. It is very catchy, the world is just HUGE and the overall story is great. It's nice that, as others have also said, in the end you get to be a hero too as a perk. In any case, if you are a fan of good old Sierra games, you won't regret buying this game.