You can find the Motorola marketing spew PDF here:http://www.gi.com/digital/dct5100.pdf
I have AT&T cable in Seattle. They currently offer HBO and Showtime with locals, Discovery and others coming online in January 03 (or so they say). I will not go into HD video quality here other than to say the signal AT&T is providing looks to be bit for bit the same as the master I can receive with my big dish and HD decoder.
Previous HD box experience: Sony HDD100 DirecTV unit and Motorola HDD-200 sidecar with a DSR-920 C-Band (big dish) receiver.
This is the bare bones DCT5100. It has USB and Ethernet onboard as well as a DOCSIS cable modem, none of which are used in my case. No 1394 ports on this unit although the platform supports it.
The guide software on this is the awful, nasty abortion known as Gemstar TVGudie. People with DSR920 (4DTV) C-Band boxes complain about that guide. It is bliss compared to the POS that is Gemstar. The Guide data provided by AT&T has robust information in it but the presentation is awful, with more screen real estate dedicated to SPAM than to guide data.
The box has SPDIF and COAX digital out. It converts audio for all analog cable feeds to digital as well. This is a nice touch.
The box defaults to 480i on the YCbCr output. You need to enter the service menu to switch it to 1080i (or 720p or 480p). You do this by turning the power off on the box and pressing the
button on the box. Use the cursor keys to move around and set the output mode.
The GUI/Guide is displayed only on the YCbCr output if you set the output to anything other than 480i. This is actually preferable, more on that later.
The box down-converts HD and sends it out the SVID and composite ports and simultaneously spews HD on the YCbCr ports. It up or down coverts as needed depending on the connection.
Use with a ReplayTV: great once I got the right IR code set selected on the Replay. Because the DCT5100 only displays the GUI/Guide on the YCbCr ports if you set the output to anything other than 480i you end up with a perfect mate for an outboard DVR. When used with a Replay (or Tivo) you get NO GRAPHICS from the box on the SVID port as long as the YCbCr output is set to something higher than 480i. With a bit of tweaking of the IR code timing I have this box tuning fast enough such that it's a seamless extension of the ReplayTV and because the box does a very nice job down-converting HD content I can timeshift from that source. It's nowhere near as good as being able to record actual HD, but it's much better than regular analog or digital SDTV.
Gripes and observations:
The only complaint I have about this cable box, other than the atrocious guide is that the black level on the YCbCr output is too low. But, oddly, SDTV content up-converted *by the box* looks OK. Only stuff that comes from an actual HD feed like HBO-HD or Sho-HD is too dark. Even the up-converts broadcast by HBO-HD are too dark. This leads me to believe that they calibrated the HD output of this box by feeding it an SD signal and calibrating against the up-conversion performed by the box. Motorola's HDD-200 side-car has the exact same problem while the Sony HDD-100, my HTPC and a buddies Mitsubishi DirecTV HD box do not have this problem. Motorola needs to address this, nobody else has this problem and it makes Motorola look bad in the eyes of the HT crowd, who will be the first to adopt this box.
Quality of the de-interlacing and scaling performed by this box: mediocre. Very few people on this forum will use this feature, but I thought I'd throw it out there. It slaps black bars on the side of the 4:3 content in a 16:9 window so if you use it you better have a DLP or LCD display otherwise you're going to get burn in. I cannot see anyone with a modern HD display using this feature. Now if the de-interlace was provided Faroudja DCDi or Silicon Image SIL50X then I think I'd be using it.
On the plus side this box is FAST. The UI is fast, the guide pops up fast (not that you'd ever want to use it). It tunes both analog and digital cable feeds very quickly.
If they got a different guide and fixed the black level output on this box it'd be near perfect.