I like how quickly it can be set up for your employees to use! We have several people who are not tech savvy at best but this lets them jump right into using trilian with no problems.
Sometimes we need some clarification about certain things which they don't understand fully well enough yet (such as file sharing) - however overall its been smooth sailing since day one!! My only issue would probably say has more doe wth our end than anything else because sometimes there could easily just seem too many options/features out here somewhere where someone might get confused / overwhelmed :) But again once an option makes sense then thats great. As far sending messages between departments within my office goes i've had nothing negative from other colleagues regarding what their experience was doing theirs either way :).