I haven't used it for a while, but I thought it had an indexing mechanism that would let you tell it what you want and it would tell you the tapes you need and the order to restore them (for full + incremental cases). And it could re-index the tapes if you lost the disk copy. Maybe that doesn't fit your use, but it seemed handy.
In general it is massive overkill for what I"m doing. Even if I wanted to switch backup solutions and move my backups to Amanda it would not be worthwhile to get this as an add-on because of the nature of the data I am dealing with.
Case in point I have about 300G of data that one of the scientists copied over to my server from a piece of scientific equipment. That 300G was never in my backups and I never want it to be. But he needs it archived.
Amanda is just way, way too too big for this.
In 2 weeks I've got a program written that is tailored exactly to our needs. THat's probably less time than it would have taken me to deploy Amanda. And it would not have been tailored precisely to our needs.