If I had to describe Zyxel's NSA-220 NAS server in a few words, I'd say it's like --minus the intimidating amount of features and plus RAID functionality.
The Sinology DS107+, at the time of reviewing, had by far the most features and the most robust, easy-to-use Web-based management. The NSA-220, on the other hand, offers fewer features, while it does come with a similarly impressive and intuitive Web interface. I tried it out briefly and was very happy with it. From creating RAID configurations and user accounts to setting up shared folders, I didn't have any problems and was able to figure things out the first time around.
The NSA-220 is a two-bay NAS server that supports RAID 0, RAID 1, and JBOD. The NAS doesn't have high-end features such as support for IP cameras or built-in Web photo management, but it does offer FTP Server, Media Server, print-serving capability, and a download service. It supports external USB storage and can quickly copy an entire USB external hard drive's contents onto its internal storage. It also comes with an interesting feature called "Broadcatching" that keeps tracks of RSS feeds.
Design-wise, the NSA-220's hard drive bays are easily accessible, and you can intall/replace the hard drives without any tools. You do, however, need to unplug the NAS server from the power and the network to reach the hard drives, so it seems the device doesn't offer hot-swapping capability.
Check back at CNET.com soon for the full review of the product. If you can't wait, the Zyxel is available now for around $220 without hard drives, which is a reasonable price.