I agree with your comment that the main advantage of time machine is that it is easy to use and is low maintenance, so users will actually have backups. It works well for incremental backups, but may not provide a permanent archival snapshot of a system on an old date. The reason for this is that it prioritizes recent changes over older data if backup space is limited. The recommended solution is to have a Time Machine drive be several times larger than the sum of the volumes that it is backing up, but this is not always feasible, so it is good to have a secondary mechanism for occasionally archiving critical data.
Time Machine will make it easy for users to recover data, from a local backup, that they recently lost on their boot drive, without the need for I.T. personnel intervention. Without Time Machine this problem typically goes unaddressed and users just suffer in silence. As an I.T. manager you will probably be called upon to assist in storage and recovery of archival data, or may need centralized management tools not provided by Time Machine. So my feeling is that Time Machine would be a great addition, one that would make your Mac users very grateful, but it won't supplant your need for other archival or recovery tools.