I'm only 1/4 of the way into Slow Productivity but I already have some reservations about the book, similar reservations to the ones I had about So Good They Can't Ignore You.
In both books Newport makes a nod towards the privilege of being able to choose what you do, but does nothing more than nod towards it. In So Good They Can't Ignore you he never tackled the ideas from Scarcity directly to help more than affluent workers have any type of autonomy over their work and thus be able to apply his principles.
I do like Newport's writing, but have to acknowledge that I'm an affluent white dude so he's speaking directly to me.