What factors may have led to failure? Also, can someone recommend any good books on the Battle's participants, preferably firsthand narratives from veterans of things like the 101st airborne (which, correct me if I'm wrong, held a city within the bulge) experience of the war?
The Germans attacked on December 16th 1944, during an extended period of bad weather. That grounded the US Army Tactical Air Forces, but made the roads in the Ardennes forest icy. The road network in that area of Belgium was rather sparse, and the Germans took to long, capturing one choke point, the small village of St. Vith. They never did capture the large village of Bastogne, which was held by the 101 Airborne Division and was a critical cross roads.
The German's had limited fuel supplies and they intended on capturing Allied fuel dumps. That did not work out for the Germans. One fuel dump was blown up, right in the face of Kampf Gruppe Pieper.
The best book about the 101 Airborne division in WW II is "101 Airborne: The Screaming Eagles in World War II" by Mark Bando.
There is also "Band of Brothers" which was turned into a television series. It looks at one company of the 101 Airborne Division. However, the author of that book, Stephen Ambrose is not well regarded on this sub-reddit. By the time Ambrose wrote Band of Brothers, he had become a lazy historian. In books that Ambrose wrote after the "Band of Brothers", he was charged with fabricating quotes, getting basic facts wrong and the serious crime of plagiarism.