I got my coupon for my convert box last Friday. Radio Shack didn't have any of the Zenith boxes in stock, so I went to Best Buy and got the Insignia box. I connected my CM 4228 antenna to it and I was amazed by picture quality, tuner sensitivity, and the ability to change picture size.
First, the picture on the analog TV has never looked so good. Second, on the initial scan it got 44 digital channels (they count all sub-channels as separate channels) and I have since added five more manually. Third, you can set the output for either a 4x3 or 16x9 screen, and there is a "Zoom" button on the remote that lets the box adjust the picture size according to "station program format", or you can set it to "letter box" or "full screen". If it's set to the automatic "station program format", HD channels are letter boxed, SD channels are full screen. If an HD channel is showing a 4x3 picture you need to go to full screen mode, otherwise you have black bars on all four sides of a tiny picture.
As for the tuner sensitivity, it beats the OTA tuner in my Dish ViP622 DVR and our new Sony XBR4 TV. I can get three Sacramento channels with it here in San Francisco, not just one like on the other two tuners, and a station from San Jose that occasionally breaks up on the other two tuners is solid on the converter box.
I hooked it up to the Sony XBR using the yellow-red-white cable that was supplied with it, and the picture is comparable to the SD picture I get from Dish Network. For $19.95, I've got a nice little receiver here. Yes, it's only SD, but the features it offers are really nice.
CNet has reviewed four boxes... the RCA, the Zenith, the Insignia and the GE. You can find it on their web site:
Which (nearly) free DTV converter box should I buy? - CNET Reviews.
Larry
SF