All the usual, variety is the enemy of efficiency (now, show me one single Windows house that has the same computers on every desk and I'll show you a company that hasn't been around for 4 years), skills aren't transferrable, free isn't free if you buy your distribution, etc.
However, the part I don't like is that it's a bashing-the-myths of Linux article and not a straight-up comparison on a level playing field. They look to be trying to go that way in the beginning, but then they add in the same false asumptions about the Linux deployment that the Linux weenies assume about Windows deployments.
The answer is clear, buy a Mac. :-) JK