Fallout: New Vegas graphic novel All Roads was already available with the Fallout: New Vegas Collectors Edition, which I am sure many fans decided to purchase. However, the graphic novel is now available to download for those who missed out on originally grabbing it.
Available from Dark Horse Digital or iTunes for $2.99/£1.90, Fallout: New Vegas All Roads was written by the game's Creative Director, Chris Avellone. The artwork is provided by Jean Diaz (Incorruptable) and Wellington Alves (Shadowland: Blood on the Streets).
Before you decide to commit to 48 pages of Fallout, you may want to take a look at the preview at Dark Horse Digital. Whatever you decide though, you cannot go wrong for such a low price.