I have to admit, I LOVE the movie starring Will Smith that was made out of this classic science fiction book. I've been wanting to read more classic sci fi anyways, so I was particularly excited to read this one. First, my comments on the book as unrelated to the movie:
The only other Asimov I've read was a collection of his short mystery stories, and this actually reminds me quite a bit of those. There isn't much of a narrative thread through the book, it's rather a collection of closely related short stories, each of which presents a mystery or problem to be solved. It's always very cerebral, and always solved by the end of the story. Asimov clearly was possessed of a brilliant mind, both for problem solving and for science fiction. The writing is spare; there is not a single word wasted, and I enjoyed every page of it.
Now in comparison to the movie: the plot of the movie is almost entirely original, though it pulls important parts from the book. The character of Dr. Calvin is very close to the book, and the moral dilemmas presented are very much inspired by Asimov's. It was interesting to see what bits and pieces were lifted from the book and worked into the storyline of the movie, and I think that the movie actually did a very good job of emulating the atmosphere and intention of the book.