What are you using it for ?
As at $1200 gaming PC it's a fail. A PC in a standard case with a reasonable power supply will crush it for less money. The video card is http://www.anandtech.com/show/6181/nvidia-quietly-releases-oem-geforce-gtx-660
OK, but not leading edge. I wouldn't assume the case can handle something with higher heat generation even if you figured out how to get a higher wattage PSU in place.
As a small PC with good components its a win with people willing to make trade-off to get the small case size. Buying this PC (or a laptop or an all-in-one) with intent to upgrade is probably not a good strategy.