The movie was better, I felt - although that was most likely down to Forest Whittiker's performance as the odious Idi Amin.
The book was enjoyable and perhaps I'd have enjoyed it more had read it first. As it was, I was hoping for more of an incite to Amin - but the story revolved more around Garrigan. Amin is the interesting character here - and again perhaps that is more to do with Whittiker then the book. Amin didn't jump of the page as he did off the screen.
Still an enjoyable book though, quite different from the film. Unfortunately you have to put up with Garrigan for the most part and he's an annoying little git - wholly intentional of course but still, annoying.