the demo of this game is really fun but is it worth it the money. like games like this one

It must be months since I last played it.
I went twice through the game with lots of restarts the first time. Many great moments and even today I cannot get some of the battle melodies out of my head (like the mowmow music on some maps) :)

Yes, it is a great game. It has a great story, charming characters, a combat system to master, tactics, strategical decisions... Some of the minor quests are really moving and well written.

Unless you know The Dark Eye well, it is much better to start with one of the already made characters. The better, the hunter. Trust this. The developers did not want to let players make their own characters from scratch, since the system is not easy at first and it is easy to unadvertently make a really bad character. But when you have experience levelling your characters, you might try your hand at a new one, if you are so inclined.