We recently installed 3 Astaro 220 Security Gateways in locations that we upgraded to cable Internet connections. Our services integrator (Integrity by CELT) was able to bundle them via a lease with our Internet costs and gave me a couple of training sessions to manage them. While they weren't cheap, they were very competitive with SonicWall's pricing on similar devices.
What really sets them apart, though, is the browser-based software interface. They're just plain easy and very intuitive for anyone with a moderate understanding of network technologies (I'm no guru in terms of networking, but nothing is hidden in jargon so anyone who has handled firewall/content filter maintenance before will have no problems). Visual cues make it obvious which interfaces are working and what they are doing and the "dashboard" (the homepage) provides all of the essential connectivity information before you have to dig in any further.
Although I had looked at specific content filtering devices to supplement our existing firewalls (Cymphonix makes some incredibly powerful products that can not only lock the students down but handle bandwidth shaping quite nicely), for one price (and one device to manage), the Astaro's were able to handle a whole range of tasks quite well. This data sheet lists everything they do, but ours seem to be doing a fine job with proxies, the usual suspects (MySpace, et al), malware detection (it's already nailed malware via HTTP and POP3), IM, and media streaming.
The software also includes Quality of Service and the device supports several different zones, to which rules for filtering, QOS, etc., can be applied individually. DNS and DHCP are no problem either.
Obviously, all of these services are available in a variety of products. However, the Astaro's bring everything together in a single, solid package that is easy to manage and highly effective at handling a variety of networking issues. Highly recommended!