For years I have been playing around with all kinds of computer based TV and multi-media solutions and toys: Windows MCE in its various editions from 2004 to Vista, early versions of MythTV and proprietary stuff. Until now none of these where really at a point where they were actually useful for a family room:
While Windows did have a reasonable UI from the start, the fact that it recorded to a highly proprietary format with nasty DRM implication was a deal-killer right from the start. Some of the tuner-cards (like ATI) attempted to mitigate this by bundling plugins for MPEG-2 conversion, but these were implemented rather clumsily and had frequent failures.
MythTV was – until recently – also more of a geek toy: nice for my lab or office, but nothing I could really throw at my family. Now, with the 0.20 config found in the Gutsy release of Mythbuntu, MythTV takes a rather large leap towards usability.
The UI is basically usable and driver support (especially for the tuner cards) is becoming acceptable. I am using an WinTV HVR-950 USB stick now with my digital-over-the-air setup and there is not a lot more I could ask for in terms of device support.
The proprietary NVidia drivers are good enough and support the motion extensions that are needed to offload motion processing to the GPU.
For audio, I require at the very least S/PDIF support (mostly for lossy Dolby Digital, but there is no other format like e.g. MLP being used for digital TV at this time), which has been quite painful, but ultimately doable.
There seems to be decent remote support, but I am right now still fighting with my old ATI Remote Wonder (I think that I will cave in here at some point in time though).
The by far most important factor for family room usability for me is RTC wakeup: I could not near having a computer with its nasty fans running all the time. Enter ACPI controlled RTC wakeup: using a couple of scripts, I was able to make the MythTV box boot up in time for any show that I wanted to record. Very cool.
One thing that I was fighting with in the end was a problem with the way MythTV could be shut down automatically after an unattended recording session. For this, MythTV provides mythwelcome(1) which is a helper program to start the MythTV frontend. The trick that made is work for me was to instruct mythwelcome(1) to not start mythfrontend(1) automatically: This overcomes a problem with session management in Ubuntu and mythwelcome, and allows the box to shutdown automatically after it completed recording.
Bottom line is that I am quite happy with my MythTV box for now.
 There are quite a few of tutorials on ACPI wakup out there, many using nvram-wakeup. Discard all these, and only use those centered on /proc/acpi/alarm, instead (if you can).
 Mythbuntu Gutsy is actually quite smart about using mythwelcome(1): You only need to go into /etc/mythtv/session-settings and enable the welcome shell. No need to change the mythstartup.sh script.
 Press the ‘i’ key while in mythwelcome(1) to configure this.