I ran Mythbuntu for a few years. It was pretty friggin' sweet:
1. Automatic commercial skipping - worked *amazingly* well
2. Web access for scheduling and watching shows - it would transcode on the fly to mp4 and you could watch on your phone/tablet/whatever
3. A nice 10 foot interface for emulators, music, etc...
4. Plugins for all kinds of cool stuff - integrated Skype calling (a popup would appear on TV showing you caller ID, hit a button and TV pauses so you can answer) ZoneMinder, burning DVD's of TV shows with a few keypresses (used this for my friends pretty regularly)
Never had too many problems with installation/maintenance. Had some difficulty getting an old ATI RF remote set up, but it was mostly configuration, once set up it worked flawlessly.
Some guy on the forums had a crazy setup with something like 8 CableCard tuners and a few TB of disk space in a monster server in his basement, with thin clients acting as front-ends to the TVs in his house. Had it wired into a multizone sound system, controlled the whole thing through a web page on his tablet, or phone, or whatever. Pretty slick.