Apart from Swedish and Danish crime series, as being more known and available, I have recently discovered Norwegian related creations, some of them almost 10 years old. And I can say I like them, not found any primitive or annoying stuff.
Det tredje øyet is definitely worth watching, but it is rather Beck-Wallander type of series than modern/recent Scandinavian crime where thrill and suspense, on the one hand, and chases and felonies happening, on the other hand, are not exclusive notions. Inclusion of dreams and visions does not provide big additional value, and the leitmotif tends to fade away sometimes, particularly in the first episodes. The ending could have been more sophisticated as well, although I liked that mysterious elements did not bring upon the real solution which was mundane, arising from daily police-work.
As for the cast, the performances were good, but more as a team, no leading/finer ones. "Only" 7 points from me as I had previously seen Øyevitne and Kodenavn Hunter, for example.