In an interview at Melbourne's linux.conf.au conference, Linus Torvalds called the standard file system of Mac OS X "complete and utter crap." Mac fans are only slightly outraged, pointing out that HFS+ isn't really "complete and utter crap," rather, it's just slightly crap-ish.
In the Sidney Morning Herald online, Nick Miller reported his Q&A interview with the originator of Linux. He asked Torvalds about the hype surrounding the releases of Windows Vista and Mac OS X Leopard.
According to Torvalds, "An o/s should never have been something that people (in general) really care about: it should be completely invisible and nobody should give a flying f*** about it except the technical people."
It's stupid - when you make a big deal about something like Vista or Leopard a lot of it is about things I don't consider to be the operating system. It's about the visual shell around it.
The fact Microsoft tied the two together so much actually caused them problems, not just the legal problems. If you manage a thousand clients, or a hundred thousand clients which is not at all unheard of, you sure as hell don't want to point and click at them. In many ways Microsoft has had to fix the design mistakes they made when they thought the graphical approach should be a very intimate part of (Windows).
To Microsoft and Apple the o/s is important as a way to control the whole environment, from a marketing and money-making standpoint, to force people to upgrade their applications, and your hardware.
When asked to choose between Leopard and Vista, Torvalds came down on the side of Leopard. Still, he said Windows was easier in some ways to program.
On the other hand, (I've found) OS X in some ways is actually worse than Windows to program for. Their file system is complete and utter crap, which is scary. I think OS X is nicer than Windows in many ways, but neither can hold a candle to my own (Linux). It's a race to second place!
Now isn't the time to go into the relative usability and niceness of Linux and Mac OS X as a desktop environment. Of course, Torvalds would find Linux better. It's his OS, after all.
At the same time, few Mac programmers would raise a ruckus about Torvalds' shots about the Mac file system. Apple keeps improving HFS+ with journaling and various new features. Still, it's long in the tooth and developers always look forward to something better.
Still, could it be that Torvalds hasn't really looked at Leopard's new file system changes for programmers? Leopard actually provides several new APIs for file system notifications. For example, a new FSEvents framework helps applications receive updates of file system changes.
If you're interested, take a look at a long discussion of Leopard's file system changes in an article by programmer John Siracusa at Ars Technica.