One of the greatest TV Series of all time.
This is my opinion, all opinions are subjective.
Iv'e seen all episodes and every season, iv'e been re-streaming old episodes, currently season 2, and i believe this is one of the greatest TV Shows of all time. The earlier seasons had a little bit more lightness, they tried their best to add a bit of humour, but the last couple of seasons has become more serious. I personally like the seriousness of the show, The Closer got more serious as well when it was on the air. I'm hoping that Major Crimes continues to stay serious and tones down the humour a lot more. The white supremacy case from this year made last season more serious, but when everything goes back to normal i'm hoping it will be 100% serious or at least 90%.
The light humour elements are understandable considering the powerful storylines, it doesn't ruin the show, if they go overload on the lightness it will start to look like "Castle" and i know that the writers of Major Crimes will not be as foolish as to go that route.