Sum was chosen by Time magazine for their Summer Reading list, and selected as Book of the Week by both The Guardian and The Week. In September 2009, Sum was ranked by Amazon as the #2 bestselling book in the United Kingdom. Sum was named a Book of the Year by Barnes and Noble, The Chicago Tribune, The Guardian, and The Scotsman.
Sum received recognition for its popularity, being featured on Time magazine's Summer Reading list, selected as Book of the Week by both The Guardian and The Week, and achieving the #2 spot in the UK bestseller charts in September 2009. It was also named a Book of the Year by Barnes & Noble, The Chicago Tribune, The Guardian, and The Scotsman.