Underworld is a big, sprawling, savagely intelligent, breathtakingly ambitious and unbelievably beautiful work of art that confirms Don DeLillo's status as probably the best American novelist alive.
It is the book David Foster Wallace would've wanted to write; but could never - despite his exceptional artistic wizardry and flashy, pyrotechnic prose. The reason has something to do with the difference between brilliant (which David Foster Wallace undeniably was) and truly deep (which Don DeLillo is and DFW wasn't - though he did sometime veer dangerously close to it).
It is a nonlinear (both in time and in narrative structure) fragmented-though-deeply-interconnected tale of several different characters whose lives are tied together by the ball that starred in the shot heard around the world and its journey through their lives; and another earth shaking development that unfolded on the same day - the successful atomic bomb test of the Soviet Union - which also affects directly, as well as indirectly, the destinies of the numerous characters in the book.
Don DeLillo has given us in Underworld, a true masterpiece, whose incalculable artistic merit confirms his status as probably the greatest novelist of our age - a fabulous, fabulous achievement indeed.