The book is definitely worthwhile reading. It certainly casts a different light on Peter Falk. A lot of what prevented more episodes from being made was his own doing. He allowed the show to go way over budget by disregarding shooting schedules, spending multiple extra days reshooting and “perfecting” scenes. He hired his friends without permission and allowed them to interfere with scripts. And he was responsible for much of the excessive humor. I agree with what has been stated that the lesser Columbos are still decent, but it is a shame that certain things could have been so much better.
You have to read the book for the details. Her behind the scenes control of the episode on all levels (which was all Falk's doing) is the reason why her daughter is in the episode among other things.