The first season of this show didn't really work for me, although the second and third engaged me more; the cases were better, the tone was better judged, and the grim atmosphere had something behind it in terms of narrative and character. The fourth season doesn't return to the superficial feeling of the first season, but there is something that doesn't quite work about it.
The cases do not seem to flow quite as well; in particular the first episode set in South Africa didn't really work in terms of being dramatically engaging, and the second episode seemed a bit messy in what it was doing. The third and final episode works much better because it has a lot of focus on Wallander himself, while also producing a case that is intriguing and has personal stakes. In this case I also liked the destructive nature of 'success' in the context of the investigation – this returned to the feeling of Wallander being a destructive force, spreading the grimness beyond himself. This element gives Branagh something to work with, and he rewards the episode for it. By contrast the other episodes he is more functional in his delivery, which is perhaps why they did not work as well for me.
Production values remain high, and everything has a great atmosphere, although I didn't think the South African episode worked with its location combined with the atmosphere they tried to deliver. The fourth season doesn't return to the weakness of the first season, but for me it was not as good as the middle two seasons – although the final episode does do a lot to help it go out in a good way.