Why the changes from the book??
Read the book. Watched the show.
Why on Earth does the scriptwriter need to change a lot from the original novel?
Stephen King writes timeless books.
The script suffered changes that makes the show very 2010's... and, in 10 years, will be obsolete (while the book will not).
--- few spoilers below ---
- We're losing some of the "epoch intimacy" with Jake when it was decided in the show he'll have a long time partner (Bill) ; that was preferred over voiceover. In the book Bill has a much smaller role.
- Why the need to add these unrealistic "you shouldn't be here" - especially the dead (?) woman after her car collides the phone booth? The Yellow card man does enough to remind us Jake is not in his own timespace.
At that time Jake tries to call his dad and says... "Dad?" over the phone so that we all viewers understand! But his dad must be 5 (or less) in 1960! That's not in the book for a reason...
- Jake should have came back to 2016 more often (one or two more times).
The script does cross the T's and dot the I's. Way too much.
And why 8 episodes and not 10? Many scenes in the show needed a smoother (longer) beginning and ending, it seems a lot has been cut.
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All in all not bad, and I'm glad a pretty good tv series was made from the book.
But it could have been a cult show.