I just wanted to post my experience with Comcast HD in Little Rock. My install was scheduled for Thursday between 10 am and 2 pm (I asked if they would let me come into the office and pick up the box, but no, they would not).
The installer didn't show up until 4:00 pm, and only after I had called the central office 3 times wondering where they were. They are not good about even calling you to let you know they are running late. I'm a Support Engineer for Sun Microsystems, so it's hard for me to believe the lack of professionalism from their install contractors. If they are running late, that's one thing, but I would expect at least a courtesy call to let me know their ETA. I did receive a $20 credit on my bill as a way of saying "we're sorry for being late."
The installer brought a Motorola 5100 box and a fairly thick looking cable which is basically component video + RCA audio, all 5 wires in one thick white cable. I used my own cables. He didn't seem to know what TOSLINK was for audio, and was kind of surprised that I didn't need to hook up any RCAs to my stereo. The install went very smoothly.
My set is a Sony 40" XBR. I checked both SD and HD broadcasts, and was impressed and a little surprised that right out of the box the STB was configured properly for my television. HD broadcasts were sent in 1080i with a 16:9 aspect ratio (of course), and when I change channel to an SD broadcast the box outputs a 480i signal to my television, which causes it to resync and I get a 4:3 aspect ratio so the image is properly zoomed on my TV. The color is a little off on the SD broadcasts for some reason, and this seems to affect both the component outputs and the S-Video output (I connected S-Video into my television also so that I could A/B the SD channels). The color isn't too noticeable most of the time, but watching a few minutes of the Simpsons on KLRT it seemed like I might be getting a little bit of green push. Overall, SD picture quality is slightly worse than watching on a non-HD digital cable box.
When I first tuned to HBO-HD and SHO-HD, I was getting some pixellation and MPEG artifacts every few minutes. I called Comcast and the operator said some of the "rate codes" on my account were not setup properly, and they reconfigured something on their end. After a couple of hours, the MPEG droupouts cleared up. This seemed to affect only the HBO-HD and SHO-HD pay channels.
One other thing to note: This box must have a much more powerful CPU than the other digital cable boxes I've used because channels change much faster. Also, the painfully slow channel guide is much faster. Now screens re-draw instantly. They still have the same fugly guide with banner ads on it though.
The two local stations (ABC(?) affiliate and KTHV CBS affiliate) seem to be pass-through of the exact same signal you get from an OTA receiver. Of course KTHV is probably the best quality. I've always been very impressed with the HD programming on CBS.
ESPN-HD is really lousy. They are simply stretching SD material to a HD resolution (not sure if they're using 1080i, 720p, or 480p). Eventually they may broadcast some games in HD, which would be nice, but overall I'm not impressed.
HBO-HD seems to have the most movies in pristine 1080i and Dolby Digital 5.1. One of the first movies I watched was Shrek in 1080i and DD5.1, and it was amazing. This is what HD was made for! SHO-HD seems to be broadcasting only 50% HD and the rest of the time it is a pillarboxed SD version of the movie. Also, it seems that Showtime has less movies that are Dolby Digital 5.1, and more that are just 2 channel Pro-Logic surround.
Overall I think it is a good service, especially due to the low up-front cost (you don't have to buy the box). If you're already receiving digital cable it's especially a good deal because it won't cost you anything more per-month to swap your existing digital box for a Motorola 5100. If you're not getting digital cable there is a $5 a month box rental fee.
I live in an apartment complex where I can't get satellite so digital cable or OTA are pretty much my only options. This seems to be the best HDTV solution for me so far, and it's kind of future proofed because I don't have to invest any up-front money in the box.
Anyway I'll post more information after I've had the box a little longer. Let me know if anyone has questions about the service.