I've never owned a Mac before, but I bought a MacBook Pro (17" display, 2GB RAM, 160GB 7200rpm drive) last August as a replacement from my Compaq. I got it mostly because I've noticed that the students in my Linux classes (primarily technical courses: Internals, Sys Admin, Device Driver, Kernel debugging, etc) have been Mac owners.
So far the Mac is ... "okay". On a scale of 1 to 10 I would give it a 6 or 7. Overall value for the money I would say is below average. In terms of innovative features, I would give it a 9.
The machine itself is overpriced, IMO. For the money I spent, I could've gotten two "PC compatible" laptops. Had I purchased a PC laptop, I would've installed Linux on it without booting Windows at all (and then taken my Windows CDs back to the store for a refund!). I would probably use Kubuntu with virtual machines running RHEL, SUSE, and Ubuntu. And maybe a plain Debian as well.
I do like some of the innovations of the Mac interface, though. I like the Ctrl-mouse wheel to zoom the desktop, hitting F11 to clear the desktop and then another F11 to bring it back, I like how the Airport locates wireless networks, and I like that it doesn't have a fan!
But I miss having windows that snap into place when they get near the edge of the screen or another window, I miss having multiple virtual desktops, I miss a window manager that allows me to customize the startup configuration of an application's GUI, I miss my Kontact one-stop news organizer (mail, RSS, news reader all in one), I miss frequent updates to the Java 5/6 JVMs, and I
really miss the programmability of the KDE desktop. (I cannot for the life of me figure out how to mark a shell script as executable on OS X without using a command line. Weird!)
Anyway, I'm no Jobs fanboy. Nor Apple. When I'm ready to spend laptop money again (probably a year or two), I'll be getting a quad-core AMD machine.

It won't be a Mac. Oh, and I'll wipe OS X from the machine I'm using now and put Xen on it with multiple Linux distributions...