It depends what you want to use it for. Mac Minis are known for a great media center computer connected to your TV. Looks a hell of a lot nicer (and doesn't take up that much room) in a TV stand compared to a clunky PC comparable.
Seriously thinking of picking one up with the twin 500 gb drives.
Have a quad core but it's large and noisy and runs win7.
This looks a good match for an iPad.
Small but perfectly formed....