After having watched all twelve episodes of this Dutch television series, it is obvious to me that this series is one of the best Dutch television series of the last decade: well written, very good acting (espcially by Sylvia Hoeks and Kees Prins) and beautiful cinematography. In "Overspel" the storyline and the development of the characters are more important than fast action scenes. Even though "Overspel" can't reach the extremely high level of the Danish series "The Killing" (a.k.a. Forbrydelsen), I can very much recommend it. For non Dutch readers who have become curious and would like to watch it: the DVD-release has English subtitles.
Addition after watching season 2. Season 2 of Overspel is again of very high quality and the acting is, like in season 1, on a very high level. Especially Kees Prins and Ramsey Nasr are sublime as father and son Couwenberg. Of course Sylvia Hoeks plays her character Iris very convincing too. The tension in season 2 is increasing from episode 1 until the final episode 10. I will not go into further detail, but I've enjoyed every second of this season a lot. I'm looking forward to the 3rd season, which has been filmed already (if I'm well informed), or is in the process of being filmed. Can't wait!