In general, I found the HN1200 to be a well-implemented NAS. Setup was easy, performance was decent, and the administration menus were clear and easy to use. I turned up a couple of bugs, but these should be easy to squash with an update.
As far as price, Hammer offers several alternatives, but you can pick up a one Terabyte version for under $500, which is a pretty good price and comparable to another dual-drive box I reviewed last year, the Maxtor Shared Storage II. Feature-wise, except for media serving and backup, the box supported more functionality than the Shared Storage II and had many capabilities that a small business or power home user would want. Whereas the Shared Storage II didn't allow user disk replacement, the HN1200 does (although I had to break the "void your warranty" sticker).
I would have liked to have seen backup software included with the HN1200 and have the ability to spin-down idle drives, but these are not show-stopping omissions. Hammer may not have the name-recognition of Maxtor (now Seagate), but if you're in the market for an inexpensive, two-disk NAS that's easy to set up and use, Hammer's HN1200 deserves a look.