Libby is a fresh of breath air, she isn't your typical snarky UF heroine that get's away with everything.
Oh she got spunk alright, she got snark! But in her personal life. As a professional she is exactly that: a professional.

She doesn't skirt away page after page on pure luck. She is intelligent and she is hardworking. She is the creme of the creme when it comes to her trade.

She shows a causality toward murder that fits her profession while still showing that..
Yes, she can be disturbed.
Yes, she can be scared.

She comes across as a real person to me, with layers upon layers.