This is a very entertaining series, and I would add a star if one is a fan of the Victorian era. It is fast-paced and keeps your attention, with snappy dialogue and a pleasing tension between the two principals. The creators have done an excellent job of giving it a realistic edge, instead of the usual tea and rosewater romanticization of this era. (I suspect the latter treatments have been created by men who long for a time when women were constrained in corsets and had no rights).
As such, it is very much in sympathy with the Wildean plays that demonstrate the brutal double standards imposed on women of the time. Sadly, many of these attitudes endure today, which is why the series will resonate with many female viewers, as well as intellectually honest male ones.
The grittiness of the times, especially for women, is on full display. One gets the sense that it is the desperation of her station, as much as her father-inspired interest in crime-solving, that compels Miss Scarlet's irrepressibility and devil-may-care behavior. It is clear that she would much rather die doing the thing she loves, than moulder away in a loveless, slave-like marriage for her board. She has a spirit that has developed in the face of some stark choices. People who are used to privilege and who have never been pushed to the brink of such desperation will not understand this, but those who have will realize that this is an accurate and believable portrayal.
P.S. It is quite hilarious that the depiction of a strong woman will bring out the criminality in some people, like the commenter who wanted to leave Miss Scarlet in a cell to die, all while saying that SHE needs to be more "gentle and caring" (unlike the commenter, apparently). This merely corroborates my statement above about the persistence of backwards attitudes and unthinking double standards to this day.