Drakensang really shines, when one is familiar with the DSA-system. I actually have played DSA and AD&D (20 years ago). Drakensang I played some 4 years ago and re-read the rule system for this. I think the german version also had the actual basic rule book as pdf as bonus.
Important to know is that the basic attributes are very important, because they are checked with a D20 when skills and magic are used. Wounds, poison etc. is really dangerous because they subtract from the basic attributes and therefore all actions get more harder. Magic is costly and no instant joker. You really have to understand how all this fits mathematical together and plan what tactical tasks in combat each party member should have and skill suitable.
Take for instance Charisma. It does not just means one is pretty or not. To use the wound healing skill one has to make a D20 test against Intelligence/Charisma/Dexterity.
That means to heal someone, you must be smart enough (to understand what you are actually medically doing), have the necessary light-fingeredness to deal with wounds, and you must have confidence in what you are doing and also evoke it in the eyes of your patient.
DSA is a really good and thought-out rule set, but it's all hidden in the math.
Edit: It's a little bit hard for me to simply get to the point about, what I want to say in English language.
But I found this on amazon reviews for Drakensang. Worth quoting:
...Combat and other game mechanics follow The Dark Eye's Basic Rules . Each of your 4 characters have dozens of attributes that you put points into. These attributes all interact while doing almost anything. This is quite different from most American or Japanese RPGs that generally use one attribute or stat for each specific task. The end result is that you get more realistic characters and fewer min-max characters (such as the hulk that can't brush his teeth for sheer stupidity).