My observations:
Time warner was able to deliver -13db signal level to my cable converter box. The minimum signal strength for 100% reliable operation is -12db. It was not working very well sometimes. Digital pixelation was not uncommon. It drove me NUTS. A service call was required to bring the signal level up to -11db... for a while. The fix did not last.
WOW delivers +4db to my converter, even after I added an extra splitter to another device when I realized I had that luxury in signal strength. It works perfectly with no problems at all.
Both companies appear to use 256Kb/s streams for digital video transmission. I know some other companies have been using lower bitrates and quality has suffered. I have also compared the HD picture from the (perhaps compressed) WOW cable HD signal with an Over-the-air received signal (from channel 4) and found virtually no difference.
The Scientific Atlanta converter box that WoW has supplied me seems to have a minor framerate issue when decoding some HD programming. Setting it to downconvert 1080i to 720p forces it combine the interlaced frames and fixes the problem. I have no experience with TW HD programming for comparison.
The HD converter box not only sends an HD signal out the component jacks, but it also sends a 480i signal out via the svideo jack and includes Two sets of audio outputs. This means that I can easily record shows to my DVD recorder from the HD channels. This is fantastic to avoid recording the pan-and-scan version of shows I usually enjoy watching widescreen. Playback is acceptable upconverted back to full size. Not HD, but not unacceptable to watch something like last night's "Letterman".
I do not have the DVR. I just use my dvd recorder, so I cannot comment on the DVR service from either provider.
WOW's on-screen program guide seems identical to what I remember from last year's TW on-screen guide. The only difference I have noticed is that with TW's program descriptions the plot summary came before the actors... with WOW the actors come before the plot summary... This annoys the heck out of me because you have to hit the info button to see even the beginning of the plot summary.
Time warner's 7Mb/s internet service is usually functionally no different from my current (and very cheap) 1Mb/s internet service from WOW. Very large file transfers are the exception. I almost never miss the extra bandwidth. CU seems to load at the same speed. :)
Both companies have done well by me customer service wise. No complaints about either.
My bill with WOW HD service and 1Mb/s internet is $20/month less than time warner's premium digital service with full speed internet and I get more channels. WOW includes not only Encore, but all the Starz channels as well, including StarzHD and StarzHD-ondemand.
WOW's on-demand service seems to be a lot larger than I remember TW's OD service. There's all kinds of stuff, including Music Choice and Havoc Music video on demand.
Hope this helps.