MichaelFurlong: I would say that Arnold's Barbarian was heavily inspired and based on the books, his character matches the Conan from the books, his interests are selfish, first he acts as a thief and bounty hunter and then he wants vengeance for a grievance.
Ah, but in the stories, he was highly intelligent, albeit naive in his younger days. He was more of the primitive sort, having lived in the grey mountains of Cimmeria all his life until he tired of it and went south, but never once was he found to have gone into a situation without a thorough analysis of the situation. Tower of the Elephant, one of the earliest stories, showed this: Conan was insulted, and would have "slunk away, abashed" if the Kothian had not physically provoked Conan - which Conan promptly responded by stabbing him. His later venture with Taurus also proved that he possessed a sharp intelligence (though not as wise as Taurus') and keen senses. OTOH, Ahnuld's Conan's responses often bewilder, like punching the camel in the face, or crying out to Thulsa Doom "You killed my father! You killed my mother!" (Howard's Conan would have spat in Thulsa Doom's face, smile grimly, then tell him "Unshackle me, dog, and I will show you what power is.")
There is also something else that is inexplicably off about CtB that I can't put in exact words right now. The closest thing that I can probably relate it to is the lack of believability. I personally found it hard to relate to the characters - I like Mako for example, but found him annoying in the movie. And Sandahl Bergman wasn't a bad Valeria, but again I just didn't really feel a sense of connection with her.