"Right now, from a functional perspective, I'd have to give Mandrake the nod at the moment. I'm sure both will steadily improve, but if you are primarily a Unix user, and don't have a huge raft of Mac apps you need to run, OS X isn't quite there yet. It's fun to play with, and it is just amazingly lovely, but it is way behind Mandrake in terms of actual Unix functionality. Tread carefully. "
This echos my feelings exactly. I'm a hard-core Linux and Unix fan, and I recently bought an iBook so I could do my hacking wherever I liked. First off, I love the hardware. I bought an extra battery for the thing, but I rarely have the need for it -- the battery life is amazing. And the glowing apple is cool, too. :-)
But "in terms of actual Unix functionality" it can be rather aggravating. After installing fink and bash it became somewhat usable, but there's *still* no Java 1.4. And I'm still used to using F-10 to get the menu in emacs (which now crashes consistency on Jaguar), I haven't had to use Esc-` for years.
Compiling PostgreSql was a real chore, requiring (a now seemingly simple) patch that I did myself. And I can't tell you how annoyed I was to learn that I can't update /etc/hosts without issuing an niload command, although I guess you can say I've since made peace.
By far the worst is the lack of OpenOffice. Sure it has a new rootless X build available, but it crashes on Jaguar.... It still requires X, which is dog slow running atop Aqua. The Mac office crashes regularly when importing rtf files, leaving me with only the ever humble Abiword to edit files.... (No Microsoft Office here, uh, ever. :-)
All that said, as soon as I get word there's support for the radeon mobility card in X, I'm switching back to Debian at the drop of a hat. The Mac is nice and all, but I need some more of that four-wheel drive power to get my work done. And I sorely miss WindowMaker. :-)