The ability to use it for multiple functions from emailing clients all over campus using my mobile phone as well! It was easy enough that I could learn how quickly after 2 weeks of trying different ways (it's not intuitive).
Nothing really - its great so far but haven't found anything specifically wrong or disliked about this program yet! Using our student portal allows us keep track easily by just adding an event into one place vs having everything scattered around throughout other programs like Outlook Calendar etc..