I like that it has features to keep track of all my emails, chats, etc when I'm away from my computer.
It also allows me to send messages to users that are in groups instead of having to reply individually. The interface could be improved - some things take a while to load, which takes time away from doing other tasks. If you need an alternative to using multiple applications for email/chat/etc., then this is great! It keeps everything together so that I don't have to spend time searching through different apps to find what I'm looking for.