I use this text to teach a first-semester graduate class for civil engineers who are targeting a graduate degree with emphasis on hydrology. I've been using the text for nearly ten years. It might be a little advanced for undergraduates, but certainly is in the grasp of advanced undergraduate students.
Applied Hydrology is the text I wanted way back when I was in graduate school. Chow was still alive but had not finished the book. I was introduced to his writing in his open-channel hydraulics text, which I thought (and still think) is the best. Applied Hydrology was assembled posthumously by Maidment and Mays, who did a good job putting together whatever remained of Chow's work. I'm very glad they undertook the process and published the work. It's an important text for my discipline specialty.
Part 1 of the text covers the basics and does it well. This material is timeless and will not change much as new research comes available. Part 2 covers analysis and shows its age, just a bit. Unit hydrographs and lumped-flow routing are old technologies and while updates are inevitable, the basic technologies will not change. Chapters 9 and 10 are a bit dated as substantial work has been done over the last 15 years. They're still good, but require supplementation. Chapters 11 and 12 again contain great fundamentals but the technology is changing. The theory of linear moments (L-moments) is working its way into hydrologic statistics for fitting distributions to datasets. Furthermore, there is a trend toward using resistant statistics (median, inter-quartile range, and others) for description of the statistics of hydrologic datasets. Part 3 on hydrologic design is still good, but is also showing its age just a little. Again, the basics are great and well-explained. However, as new data become available and new analyses of those data are accomplished, new interpretations also become available. This is true especially with precipitation atlases and the estimation of n-year precipitation events, and hence n-year hydrologic events.
My observations are not an indictment of Applied Hydrology; it remains my favorite engineering hydrology textbook and I will continue to use it to teach engineers about hydrology. In my opinion, this is the best upper-undergrauate/graduate engineering hydrology text available. Like all textbooks, it is beginning to show its age because technology is not stagnant. But its descriptions of core concepts and the application thereof remains top notch.