Bang for the buck seems to be one of her major criteria, and she is tough on the higher end restaurants. She gave Finz about a star and a half a couple weeks back and pretty much said she felt like it had fallen from the Elephant Walk glory days she still remembered fondly and turned into an overpriced tourist trap, and really panned Fish Out of Water when it was working out the kinks when it first opened.
She also seems to compare like to like- the places that want to be four star are compared to Criolla's and the like, while the dives are compared to the Red Bar/Dewey Destin's, and strip mall ethnic is compared to strip mall ethnic.
I think she's a little bit generous with the stars at some of the mid-level places, but when she says a high end place is worth it, it normally is going to be an excellent and memorable meal.