This has been my main computer for over 5 years now. I have almost never turned it off. It works flawlessly. I have no performance problems. My only issues is really the number of ports and storage space.
But I agree it has an amazing feel. I used to have a Mac G4 Cube but regret selling it. These kinds of computers are like work of art you want to show the next generation to tell them about a bygone age of computing.