The negative of the show is that much of it is predictable. The powerful men have to act macho and the woman is not respected as an equal. The woman has much better instincts as a copper than the men who've been on the police force for years. The worst of the coppers is, predictably, almost a 2-dimensional character, at least through the 2 seasons I've seen so far.
The positives include that there are some sensitive male characters who give Gina a chance. The supporting cast is excellent. The plots are interesting and appropriate to the times. And the attention to detail (sexism, racism, brutality, repressed sexuality, clothing, sets, hair styles, makeup, music, dialog) makes me almost believe it really is 1956 on the set.
Having lived through the 1950s (age 11 in 1956) I can attest that much of what we see on this show was very much like this. In many work places women were considered to be either eye-candy or efficient old maids who had no life outside of their employment, This continued well into the 60s until the women's movement had some clout. It would have been even more so for Gina who would have been about 10 years older than I was in 1956.
Gina's character has to be independent enough to take on a nontraditional job, tough enough to be a cop, yet still have a sensitive side. I think Jennie Jacques manages to pull it off well.