Many people write me to tell me that the GNU Assembler (gas) sucks!
How could I ever think of using it!  Why not use "nasm" and the
one true Intel assembly format?

I too once used only nasm.  And if you are doing development under DOS
(or cross-compiling DOS executables from under Linux, which I did 
extensively in college) it is the way to go.

But, after doing lots of non-intel assembly you realize gas isn't all that
bad.

So here we go, reasons why vmw uses gas:

1.  AT&T Syntax goes hand-in-hand with UNIX(tm)

    If you are doing assembly under Linux, especially in-line in C,
    you will have to learn AT&T syntax anyway.  
    
    Intel's format, while easy to use if you are used to it, is completely
    backwards from pretty much _any_ non intel architecture.  If you are
    stuck in the world of x86 compatible chips like 90% of the world, then
    fine.  If you move back and forth a lot the benefit wears off.

2. Portability

   "ll" compiles on lots of architectures, all of which I maintain.  It
   would be a pain to have to develop separate includes and helper
   macros for just the intel architecture.
   
3. Ubiquity

   Any system that runs Linux and has gcc installed has "gas" as well.
   nasm is almost _always_ a separate download and thus a pain to require
   especially if you don't have internet access on the machine you are
   developing on.

4. Similar Feature Set

   nasm is a bit nicer in regard to options, but in standard use I have yet
   to find a feature I need from nasm that gas can't do with a little coaxing.
   (well, besides creating DOS executables, but luckily I don't have to do
   that much anymore).