I've read four of the Kurt Wallander series at this point, watched all three seasons of the Kenneth Branagh series, and watched season 2 of the Swedish series (why oh why can't we get season 1 in this country?). Fair to say that I'm rather steeped in the Swedish mystery culture. And that I know too much about Kurt Wallander. But each of these - the originals and the adaptations - show Wallander in a different light.
In the novels, Wallander is a far, far sadder character. His life is just down the tubes, man. You want to reach out and hug him, only you're afraid you'd get yelled at. After the last novel, he is truly struggling at being a police officer, but an important meeting gets him back at the station and working on a new case. He galumphs around the office each day, trying to remember his instincts.
It's really Mankell's observations of human character that make these mysteries so compelling. Because they do move rather slowly, as nothing gets done page after page - precisely the kind of mind-numbing detail that police work really is. But Mankell constantly gives us insights into the thoughts, interests, mannerisms, ideals of all the police officers at the station, as well as the witnesses and additional needed characters. As a result, when a scene with action occurs, it almost feels as if it doesn't fit inside the book and should be in a fantasy novel instead.