The Oxford Murders is pretty light-hearted, with no real tension. The plot is driven by the underlying mystery, a series of twists and turns, and some logical fables and puzzles. Some of this is a bit artificial, but it works well enough and comes with some mathematical background — Andrew Wiles' presentation of his initial proof of Fermat's Last Theorem is even worked into the plot, peripherally.
The characters and the Oxford setting, on the other hand, are used for superficial effect and never really developed. Those without any mathematical bent and after a murder mystery set in Oxford would be better served with one of Colin Dexter's Inspector Morse novels.
I bought The Oxford Murders as light reading for a plane flight from Sydney to London. For that purpose it served admirably.