At the moment it's seriously lacking in a lot of areas.
It needs better contact management and categorization, and perhaps a method for blocking undesirable contacts. Right now things are manageable, but that will change over time.
It needs an update notification system. Scheduled email summaries, IM integration, something.
It needs output services. I built a trip using "trippy" (which is a pretty cool and useful extension, by the way) but I've got no way to output it (other than a screen print).