The Art of Assembly is, itself, an immensely useful and dated piece of work. I remember flipping through this years ago. Certainly worth the read, though it's likely not worth pouring one's self into too far, as it isn't so easily applicable these days.
...unless maybe you want to write highly-optimized code for special applications, or maybe to write compiler code generators. Assembly language knowledge is still useful otherwise to understand what the machine really does.
