I've enjoyed the TV show of the Handmaid's Tale, but never read the book - is it worth it? To be honest, I wasn't as taken with it as I was with others - so much so I didn't bother with the telly series. The book was interesting, but maybe a little bit too straight line thinking for me! There is nothing sudden, some of the things the series seem to have made clear just aren't in the book at al - like how the Sons of Jacob started! But it is worth reading as it is often used as shorthand for many social mores.
As YAS said, her books aren't feminist as many understand feminism these days. There is always a woman or three set upon keeping women down, mothers, sisters, etc. Some women actively engage with the oppression of women. She is / was a liberationist.
It is that perspective I need to have a rethink about. Just to reframe some of how I think about it, and her Tweets. In that light her TWAW isn't all that surprising. Disappointing, but not surprising!