When I was in grad school, we used the 4th Edition in the Senior/Masters level computer architecture class. I still have it on my book shelf. I've re-read large chunks of it a number of times in the past 10 years (often inspired by making sure my bases are covered during job interviews).
Given that most of my career has been pretty far removed from the compiler/assembly instructions, much of the content wasn't directly relevant to what I've been doing, but I still find myself using many of the tools that are outlined in the first chapter ("Quantitative Principles of Computer Design") when dealing with performance problems or analysis in high-level-language-world, which happens pretty often.
Given that most of my career has been pretty far removed from the compiler/assembly instructions, much of the content wasn't directly relevant to what I've been doing, but I still find myself using many of the tools that are outlined in the first chapter ("Quantitative Principles of Computer Design") when dealing with performance problems or analysis in high-level-language-world, which happens pretty often.