I have used the openELEC XBMC on a few personal projects. 12v battery driven - caravan TV and
5v USB from cigarette-adaptors.
Has worked fine so far.
In the office the guys have tied it up to their phones, got the online weather, used it (with addons)
to do wee bits of video, etc etc.
The main job was to play some rolling mpegs for a display in a tent. We got a 20" monitor, and a pi easily running for over 20 hours on a leisure battery.
XBMC can have most of the things it needs downloaded using their interface (with a mouse). Little knowledge of unix was needed.
The ONLY hassle I had was writing the SD.
The first images were "dd'ed" into the device. They did not work. I cant remember which open ELEC I went for, but it does an mkfs on the SD to make two partitions. That method worked 1st time.
I can look up what I used if you need it.