Ha. I just went and read about this myself. Personally I found ubiquity really useful. I loved the way I could select a postcode, press a keyboard combo and then just type "map" to get an interactive Google Map. I especially liked the way I could subscribe to feeds of commands, most of which had a whole host of handy options. The natural language process part of it was simple, but easily good enough for the intended purpose.
The reason I stopped using it was because new versions weren't backwards compatible and cleaning up after an update became a bit of a mess. I don't know if others had the same experience?
I just want to buy some milk for my son at the grocery store
Get a cow? Although, it looks like you already tried to apt-get one...
Backed up the system lately?