This is Shuttle's first venture into this demanding category, so I unavoidably spotted several flaws in the KD20. Its elegant style, the front USB 3.0 port, the embedded SD-card reader, the easy-to-use interface, and the long warranty—at least compared to the competition— still leave the KD20 with a lot to be desired. For starters, its transfer speeds are dramatically low in all cases, and I was unable to find a compatible storage device that could exploit its USB 3.0 port. Performance remained very low even after I connected the external drives to the USB 2.0 ports, indicating that something fishy is going on. There are, on top of that, no eSATA ports since it restricts you to the slow USB ones. Also, I didn't like the lack of a secure shell interface, which would allow an experienced user to do lots of interesting stuff. Moreover, the administration interface may be simple and fun to use, but its lack of options make it pretty restrictive. It, for example, doesn't include a firmware web-update option or notification feature and doesn't inform the user about the progress of the RAID array initialization process through a corresponding bar or timer. Finally, Shuttle doesn't offer any extra software application packages, like QNAP's QPKGs, which could greatly boost the KD20's usability.

To sum up, the slow transfer speeds are the main problem of the KD20, and I think that the weak CPU is the main culprit here. I very much like its nice looks and the small footprint, but those are not enough to make a NAS server good. Shuttle should immediately look into the transfer-speed issue while also checking on the performance of the bundled USB 3.0 port since none of the three devices I tried registered even close to acceptable results. The KD20 may be one of the most affordable 2-bay NAS servers on the market, but you can find significantly better products by spending an additional 40-50 bucks.