I first watched this TV movie when I was 9 or 10, and it haunted me for a long time afterwards. Many years later I came across the book, and although this fills in a lot of the gaps that the movie leaves out, the movie does a better job of dramatising the situation without the over emphasis on the goodness of Steven's family, and the evil of his kidnapper that the book gives. It's a shame that all the details could not have been included in the dramatisation, as the full story would have made the story even more tragic, and that bit more realistic. A 5 hour movie would not be that practical though I fear.
The abuse of Steven is left up to the imagination in the TV adaptation, which is tactful to the family of Steven, but does gloss over the point that Steven was severely sexually abused and raped, and that Steven was okay with his friends suffering the same fate when they visited. These little details and many others like them make for a more frightening and even more gripping one than was produced. This is a shame, but understandable for a low budget US TV movie.
Generally, this is well worth a watch, though the book is better factually; but I'd probably give it a miss if you have young children.