I don't have any personal experience with Synology products, but it looks decent based on the specs sheet. Proper AFP and other file protocols (outside of SMB), lots of media features, drive expandability, and a decent admin interface.

I'm surprised there isn't a comparable ReadyNAS unit like this out yet. 2.5 inch form factor drives are becoming more and more commonplace for home storage, and do offer a noticeable power usage benefit compared to 3.5 inch drives.