The G4 Cube didn't sell well due to price, but the form factor was amazing for its time, and there were no performance issues, unless you were a bigtime power user, in which case a boutique, clear plastic cube with limited expansion wouldn't exactly be the ticket.
And, I take issue with saying the Quadra sucked. I had a Quadra 950, and produced huge, four color catalogs; I was an early adapter of digital photography via a Scitex Leaf digital back on a Mamiya, and had no problems. It was quite the workhorse at the time. It would feel like a slug now, no doubt, in comparison to a dual G5, but hey, we're talking 13 or 14 years ago.
(Denny Crane: "I Don't Want To Socialize With A Pinko Liberal Democrat Commie. Say What You Like About Republicans. We Stick To Our Convictions. Even When We Know We're Dead Wrong.")
Got SIMMs?