Technicaly great came that suffers from the limited part of the pen&paper RPG it is based on and the boring dialog
Both games are graphically great.
The differences come in the character customization and the way the NPCs and the story are handled.
Character customizaton is limited and kinds disappointing. You have about a dozen characters to choose from. This sounds like a lot but most of those characters are similar and there are no class/race based special abilities. My favorite class in NWN2 was the monk. Some of his special abillities were immunity to poison, illness and mindcontrol, super fast reflexes...In Drakensang every character can learn every special ability. You can have a mage learn every piece of fancy swordplay you want. The difference in the classes are just the startvalues and some caps (You can't increase muscle over a certain point for a mage...). This highly reduces replay value. The classes all feel the same. And you have no influence on what your characters look like.
The seond drawback is the dialog. It's boring. For those who know NWN2, thing about Sand's little moments (A character who in a court trial finished his pladoyer with "And above that I want to say that the dress of the lawyer of the other party makes her look like a whore in the dock district") or some of the other funny stuff ("You look beautiful, would you like to keep me warm in my bed at night?"-"I could set it on fire!"). In Drakensang, the only thing that is similar are the conversations between two of you characters in you mansion. But even those are not really funny.
Overall it's a game that could have been great but isn't.