As a sci-fi show I would place it in the middle of the pack. It has some very good storylines and the acting is well done. The sets are over all great but there are some poorly done ones. There are few sci-fi shows out there and fewer that you can watch with the whole familly. My kids are Doctor Who fans and I try to find other sci-fi shows tath they will watch. The use of the children helps wit this. Also the language and level of violent somewhat. It does have the same problem that a lot of sci-fi shows has. Too many aliens speacking the same language and breathing the same air. I understand why they do it. Cost. But it stil hurt the science.
As a cop show I would place it in the upper 3rd. Good storylines and great new take off of old storylines.