The book helps people get rid of the guilty feelings invoked by the habit (not the consequence) of procrastination. According to psychological research (detailed in The willpower instinct，chapter 6), self-forgiveness usually leads to better self-control and well-being.
That said, IMAO only the first chapter is worth reading and which deserves the 4 stars. It’s typically useful for trivial / low effort / highly specific tasks (e.g. homework, housework) but useless for creative / uncertain / high-stake tasks (especially: research, artwork, etc).
For the latter one, I recommend The war of art for the relentless mindset and this Reddit thread on time management. Just get started is the most and the only useful way to get things done.