Think Again is the kind of pop-psychology book that has several useful nuggets, and is so accessible that you'd expect to see it on "Best Nonfiction of 2021" sorts of lists—and perhaps at the airport. This isn't to be overly critical, so I'll summarize the idea: we're overconfident and don't spend enough energy trying to be right; we're susceptible to predictable cognitive biases where we are poor judges of our lack of knowledge.
If you're exposed to LessWrong-style rationalism, none of this is new or surprising. If you're not, then it'll probably be pretty eye-opening and interesting. For me, it was a bit of a slog—not because of dense or poor writing, but more that I kept waiting for novel insight. In many ways, if you liked other Adam Grant books (or perhaps, a more refined and polished Malcolm Gladwell), you'll minimally probably enjoy the journey.