What is most valuable?
Central management console. The mac backup client has improved quite a bit in the past couple years. Initially in 2010 it was very bad and would often lose your entire backup forcing the user to start again. I've had good experience with the Mac backup client running silently and keeping files backed up. We've restored from a backup and it's nice to have the ability to restore specific revisions of a particular file.
What needs improvement?
Users are allocated a specific amount of backup space, but there's no way to set that to auto increase - the backups just stop until it's taken care of. The invite process has not been easy for users. If the IT admin sets it up this seems to go fairly well, but there are many ways to screw it up. The selection of directories and files to back up can't be managed centrally, it has to be set on each user's computer.
*Disclosure: I am a real user, and this review is based on my own experience and opinions.