I'm an engineer, and I've gotten so much benefit out of that book. I read it cover to cover several times a year. It's very corny, but it reminds me of several things I often don't conciously think about when interacting with people. Sometimes reading that book is the only way I can get through the day and interact pleasantly with people.

One reason engineers can be unintentionally critical is that their job is often "find what's wrong with this thing and make it better". It's rarely "find what's right with this thing and congratulate someone". It takes me quite a bit of mental effort to switch from nitpick mode to encouragement mode. I've tried to consciously balance my criticisms by leaving a few honest encouraging comments in code reviews like: "thanks for improving test coverage here", or "glad you handled timeouts and retrys, this api has given us grief before".