I suppose one shouldn't be surprised when best-selling authors turn out to be terrible writers. The latest example to spring to mind is Dan Brown, author of the Da Vinci Code. When I finally got round ot reading the book; I simply could not believe how slapdash and cliche-ridden the writing was. What saves the book, as it saved the works of Frederick Forsythe and Jeffrey Archer in the past, is the plot.
What we really want, of course, is a writer who can dream up a plot but can also make one believe in the characters - someone like Ken Follett or Desmond Bagley.