Against The Competition...
Currently selling for $290, at that price point the HS-210 is not overpriced for a two-bay NAS but there are better value options such as the similarly-equipped TS-220 for $230 or the Thecus N2520, which is 40% cheaper at ~$180 and possibly the best-value sub-$300 two-bay NAS available.
What QNAP offers, however, is a unique fanless set-top design as well as a more refined user interface and software setup than you'll experience with Thecus. While we like the HS-210's living room-friendly aesthetics and we're happy that QNAP's QTS software is finally on par with Synology, there are a few catches to cover.
First, the concept of an HDMI-less multimedia NAS is strange to us, even if Synology also did it with the DS214play. At least that boasts 1080p video transcoding. The HS-210 has no particular multimedia hardware and something as simple as an HDMI port would make this box a more practical HTPC replacement.
Second, the HS-210's fanless design seems unnecessary because QNAP's TS-220 is extremely quiet (and it doesn't threaten to harm the longevity of your drives). More importantly, the HS-210 isn't likely to be silent anyway, unless you plan to install a pair of SSDs and we doubt that's the case -- at least for most of you.
QNAP's set-top NAS seems even more pointless when you realize that without HDMI, there isn't really a reason it needs to mingle with your other Hi-Fi gear. It could just as easily live in a closet or anywhere else with network connectivity and electricity, in which case its attractive design doesn't matter very much.
This isn't a HTPC replacement then, but QNAP seems fine with telling you it is. If you can look past that, the HS-210 isn't necessarily a bad buy. It was substantially quicker than the TS-220 -- closer to the $330 TS-221 actually, though this might be due to newer firmware -- and it's 40% slower than the DS214play while being 24% cheaper.
It's worth noting that the HS-210's upload/download performance increased about 30% after installing Seagate's NAS hard drives, but the other NAS devices might also see these gains. We won't know for sure until we do more testing, unfortunately. For now, HS-210 owners may want to opt for Seagate over Western Digital.
There aren't too many viable NAS options under $300 so we're glad the HS-210 is available. We may question some of QNAP's design choices, but the HS-210 offers a great user interface and acceptable performance for a fair price. Nonetheless, its confused sense of direction makes the box hard to recommend over rivals.
Pros: For its price, QNAP's HS-210 has clean looks, okay performance and software that is perhaps second only to Synology's but definitely better than Thecus'.