QNAP is very cost effective. The features are plenty and the speed is good. The TS-212 is their basic model and has about ½ the speed of their “business line”, less memory but at a significant less cost.
All QNAP shares one flaw that I dislike. You can’t restrict certain users from the apps. For example, you can’t restrict user “kid” from using the web server, SFTP, SSH etc but allow that user to use SMB. Basically, the security of the device is about as good as the weakest password/username/rights in your setup.
If I have my kid with user name “john” and password “123”, that username/password/right is exposed to the internet (unless you clamp down on the entire device).
Things that QNAP should improve include their iphone App “QMobile”. There’s a bug that you can’t create user play list.
There are certain unknowns that a user must accept while using a pre-built NAS such as “what happen when the hardware itself fails. Can I just pull and plug the HDDs into another identical unit and have it up and running? “.
Lack of ECC at a reasonable price is also a drawback.
Other than that, I am happy with QNAP.
I have a QNAP TS-212 or whatever. It's basically 2 hard drives that are not hot swappable....it was $150 for the NAS and whatever I put in it for drives. I've got it setup with 2 WD Reds. You need to use Reds, Blues, or Blacks....stay away from Greens in all NAS setups...power saving mode will kill your RAID in some setups. I never had a problem with mine, but read reviews that others had issues. (they're not officially supported for RAID)
QNAP does active firmware development for their systems. They can do iSCSI, CIFS, and have a lot of app features. It's a pretty solid product.
DROBO is another brand that I've heard good things about...though I had a friend lose their whole array in the past 2 years.
My QNAP lost a drive a year and a half ago to drive failure. It beeped and Emailed me to let me know that there was a failure. I promptly ordered a replacement and got it back up and running. The drive rebuild process was pretty painless. My only gripe is the unit has more features than the processor can handle. They basically give you a server with an Atom processor and 512MB of RAM in the 212TS. Some of the apps are extremely slow due to the hardware, but the RAID and disk throughput are fine. I would definitely buy another.