Just used my gubmint'-issued $40 credit and bought the box (at a local Circuit City). Got the only one they had, the Zenith DTT901. Now I'm wondering whether I should have shopped around first.
My main complaint is that the picture quality ain't great. I saw another converter box at a friend's house that looked really good on their tube; this one isn't all that sharp or punchy, kind of grainy. Definitely not as good as the analog picture I get from those stations with the strongest signals. (On the plus side, not only do I get lots more channels than I got before, but the picture quality is at least consistent among all of them, even if it's not the greatest.) I'm assuming this has something to do with the DAC chipset or the RF modulator in the box.
Box was super-simple to set up. I'm not thrilled with the user interface: there's a "favorites" function that's kind of annoying to use. You can put the most-watched stations in a "favorites" list, then hit the FAV button to access them. Problem is, the on-screen menu has a very short timeout, so if you linger too long on one station, it goes away and you can't pick from the list without hitting FAV again (plus it bumps the selection up each time you hit FAV; definitely not the way I would have designed that function).
The remote doesn't turn my TV on and off, but that's probably just because the TV is so old. (There's a list of 45 manufacturers whose sets can supposedly be used with the remote.)
Not big deals, since I don't really care that much about TV anyhow. I'd be curious to hear similar reports on other converter boxes.
Oh, and the box was $60, so I paid $20.