Other reviewers have already praised this series adequately. I only want to add that this series renewed my interest in seeing just about every film or TV presentation that Kenneth Branagh has acted in. He's been in some vehicles that weren't terrific, but he is unfailingly a great actor.
When you watch Wallander, and you see his eyes begin to well up with tears, or you see him struggling to get an answer to come out of his mouth, you really do forget you are watching an ACTOR. Branagh literally becomes Wallander and you think Wallander is a real person. It is partly the way the character is written, but much of the credit goes to Branagh.
Wallander is a man who struggles with words, so he is the opposite of Branagh, to whom words are golden. You can tell this from Branagh's interviews as well as from his performances. The visuals in the series are stunning, the plots are interesting, but it is Wallander's complex and troubled personality that really forces one to stay with the series. He's so real, so human. Don't miss it.