The ease to use, the ability for one system to pull in data from multiple sources (ie. TripIt & Expedia), that it can be used via mobile app or web browser. We love how easy it is to update our calendars with all events/conferences we have coming up - no more having to do this manually! Sometimes we are still not notified when something changes on an event page like price change.
Other than this small issue, I'm happy we made the switch to using Get2Hawaii as our booking tool. It has helped us