As you probably already know, this book is a novelisation of the 1989 Bond film of the same name, as opposed to an original novel by John Gardner. I've always been slightly wary of novelisations, as they often stick so closely to the film they are based on that you end up asking yourself "Why did I waste days reading that when I could have just watched the movie in two hours?". A good novelisation, however, takes advantage of the fact that it is not tied down by a two-hour running time, and essaentially becomes a more detailed and satisfying version of the film.
Gardner's Licence To Kill falls ino the latter category, as it adds a lot more depth and background to to the film's plot and goes to great lengths to fill in some of the movie's plot holes. The one, glaring flaw is Gardner's strange decision to place this book in the same line of continuity as his, and Ian Fleming's, previous Bond novels. Because some of the events and characters in the film were taken from Fleming's books in the first place, the choice to position this book as a follow-on from Fleming's seems ill-advised, and forces the reader to suspend a significant amount of disbelief as Bond apparently relives events that have already happened to him.
For example, Felix Leiter is attacked by a shark for a second time since Fleming's "Live and Let Die", in a chapter called "Lightning Sometimes Does Strike Twice". The shark does nothing except bite off his false limbs, which makes Bond's motivation for revenge seem a little thin when compared to the film, in which Felix had not suffered a previous shark attack and lost his real leg. Also, the character of Milton Krest, who appeared and was killed off in Fleming's "The Hildebrand Rarity", is resurrected here with no explanation or reference to his previous appearance.
Despite this, Licence to Kill is a decent Bond adventure that, in spite of it's flaws, I recommend if a) you enjoyed the film and b)you are good at suspending your disbelief. A good read overall.