That's a pretty healthy way to look at it. A general line from some authors about such things is "they haven't done a thing to my book, it's sitting there right on the shelf just fine" while a few others seem genuinely upset when the adaptations get it wrong.

I typically have no faith in an adaptation capturing the book so I'm always pleasantly surprised when it does. That says a lot for the filmmakers.

I recently caught ICE STATION ZEBRA on TV somewhere and realized I hadn't seen it before. It's a really terrific first person MacLean thriller that I thought would be impossible to film adequately. It certainly wasn't very good.