To Engineer is Human is a surprisingly relevant book, despite being 15 years old now. Some of the examples may tax the memories of younger engineers and engineering students, but that's exactly the point of this book, to emphasize the nature of engineering: improving what has already been done in the past.
I, too, found the repetitive references to a limited number of examples tiring; I suspect this was done because Petroski had prior knowledge of these case studies and wished to minimize his research by drawing on what he knew about before writing. As an amateur historian of technology, I was also disappointed that few earlier historical examples were treated in any depth, the Crystal Palace being a notable exception.
The book is an easy read. Henry Petroski's prose is easy to grasp and flows well, holding the reader's interest, despite the repetition.