So, while RASL has a few problems, the art is certainly not one of them.
I think the concept of RASL didn't have quite enough room to spread out, leaving the reader with some forced assumptions and unanswered questions. Mostly, I was left wanting more: more about the art thieving business, more about Sal and his motivations, more about Maya and her motivations, more about what drove a promising scientist to become a dimension-hopping alcoholic art thief. Unfortunately, the reader is just left wondering, even about some of the big, plot-moving questions.
In some ways, RASL is fun in the way that Mission Impossible movies are fun. That is, the action and concept and set pieces are all engaging, but don't try to make sense of it later or expect plot threads to be carried consistently throughout the story or rely on characters to be fully developed. It's good, but it doesn't accomplish those storytelling basics.