IMO, Synology produce the best NAS around (for this price point), and this is a very robust version with a couple of USB 3.0 ports (and another 2.0 port), and a solid dual-core CPU (for a NAS).
Not to be confused with a Microserver which are less targeted for NAS-specific work.
I use my older version to serve media files within my home (including to an XBMC machine) and to access securely from the outside world.
£10 cheaper than the other usual sources, although this has slow delivery.
I'd recommend this review for more details of the machine:http://www.trustedreviews.com/synology-diskstation-ds414_Peripheral_review