Now what the hell is wrong with that pic of Miss Roberta??? Lovely pic there mate!
Now, it's true that even a bad pic of Roberta is still good. But from a pure photo review sense, the not so great things in there that I can immediately see are:
Leaves in the pool, distracting and breaks up the line of the pool and water.
Weird leg and body angle/position. Hurts the overall composition and flow of the eye. Imbalanced.
Inopportune shadow highlights appendectomy scar - visual flaw on subject.
Undesireably busy background - visual 'noise' and more distraction.
Drowsy eyes and expression make her look semi-conscious and less compelling.
Wet footprints look messy, break up the line of the pool edge.
I'll bet pedonbio can clarify further and point out more (and/or refine my items a bit).
-D'Artagnian