Just received an Archos TV plus, which I'm hoping to use as a DVR, and thought I'd offer some first impressions. The short of it is, the reason to buy this thing is for its low price and impressive feature list. If you're looking for an Apple- or Tivo-like flop-on-the-couch-and-start-watching experience, this isn't quite there yet. Expect a couple of hours of setup and learning just to get going. But it's a nice little box with no monthly channel guide charge (for the first year) that integrates all kinds of digital material with your TV for about $250.
It has no tuner of its own, but uses an infrared "blaster" to control your cable or satellite box. There's no wire; it just beams the ir out the front of the box and hopes that it bounces around enough to get back to your tuner. The guide is adequate, but just that; you can record individual shows, daily, or weekly, but none of the Tivo-type options of choosing shows by title, first-run-only, or sophisticated searches. (This has evolved out of a system created to load TV onto Archos' portable media devices.)
It comes with access to CinemaNow and a youtube-like service, but you can optionally buy an opera browser that gives pretty full web access. Options for getting things on and off the Archos are numerous: UpNP, a usb port that both lets you load things to and from usb disks or turn the thing into a hard drive on your PC, or you can run a file server program that makes the Archos's hard drive accessible via your home network, either wirelessly or via ethernet. This gets you into a complex world of codecs, filetypes, etc., but so far the Archos seems pretty robust in that department.
I'm behind the times and only have a Sony Wega 32" standard TV, so I can't say what the quality is like on more modern systems. It claims to be able to play 720 files like the Apple TV, but cannot record HDTV. It has an hdmi video output (as well as a host of other options.)