Yes, Linux is a great OS, but it simply doesn't have photoshop or anything that compares to it. GIMP is a clumsy hack and is frankly like Paint in comparison.
Compared to Photoshop, Gimp might be like Paint, but compared to Paint, Gimp really is like Photoshop
Gnome, KDE and Explorer have nothing on the frankly revolutionary changes Mac has seamlessly implemented in the last few years. There are a lot of poorly implemented whizbang features like Time Machine's GUI or Safari 4's Top Pages, but there are also features like Spotlight, Expose, the new stacks in the Dock, and Quick Look.
Maybe you can check out
Call me back when Linux works with my hardware out of the box
Call me back when you buy hardware that works with Linux.