I wouldn't buy it just based on the specs alone. And the very idea they think this PC is worth $800 brand new is a joke. I mean with a GeForce GTX 650 video card? Seriously? You can build a much better PC yourself for around $600.
With that said, I have bought an "open box" motherboard and case from the Egg and never to this day (four years later) have had a problem with them. I'm sure they tested this PC, otherwise they wouldn't be selling it. The Egg has an excellent reputation to uphold. My guess is this PC was bought by someone expecting to play the latest games on it and was thoroughly disappointed.