Well, that depends. Many of the basics fundamentals of microprocessors haven't changed: there are registers to read from / write to, fetch-decode-execute cycles, interrupt handlers, ALU / FPU units, interfacing with peripheral units via address/data busses, and, or course, waiting (amongst others).
That's not to say that things haven't changed since 1996; the gigahertz barrier has been broken, stuff has moved back onto the die, and transistor sizes have gone down by nearly 3 orders of magnitude (from 35 um feature sizes down to today's 45 nm ones). However, that describes computer processing. The vast majority of processors made and used are still embedded processors, and many of those are just refreshes of models first introduced in the 80s (for instance, the 68000 or Z80 series) and have clock rates that are probably lower than anything you'd encounter in your PC (I don't know if PCI is still limited to 33 MHz or not).
So, if you already have a basic computer architecture course under your belt, then you may wish for something a little more recent. If not (and you have taken a basic digital logic course), then it's probably worth reading.
For the record, the book I used when I took my class on microprocessors (and assembly language) in 2003 was published in 1991! (Harman's book on Motorola's 68332).