The Computer Connection/Extro is a lot of fun, although it's quite a bit darker than his earlier novels. It's a pageturner; Bester's books always moved along at a fast, efficient pace, and pulled the reader along with him, but I think that book is the most extreme. Within the first couple of pages, the main character has already traveled back in time to 1770s London in an attempt to save Thomas Chatterton from dying (a favour to a friend, nicknamed H. G. Wells, who uses a time machine to transport gold back into the past in order to attempt to save impoverished artists and poet such as Mozart).
Stay away from his later novel Golem^100, though. It's a sad, often mean-spirited shadow of his best work.