It was a bit short for the price (under 70 pages, $2.99) IMHO, but the writing was good, a different take on the "alpha pair" concept common in shifter novels. In this case, two males form a pair and then have to find their human female to complete the set. I would have liked to hear more about background on Keller and Madden, how they came to become a pair, background, etc. It just felt too short, not enough about the characters, but again my preference does not align with novellas/shorter works so that is just a personal bias.
I would definitely read the others in the series to hear about her sisters. :)