I'm a fan of Hans Zimmer, but the guy has sadly just not been challenging himself with his scores for this decade. Nowhere has that been more apparent in his scores for the live-action Batman films, which consist more or less of deep techno: not unpleasant to listen to, but despairingly simple and lacking in complexity.
It's therefore somewhat fitting that Batman: Mask of the Phantasm, an animated movie that can actually hold its own with the live-action films, should have a soundtrack that easily challenges Zimmer's own work.
In fact, this in many ways represents how those films should have been scored. This soundtrack clearly takes some inspiration from Elfman's work on the Burton films, but this never even approaches the realm of plagiarism as the score evolves into a thing of beauty in its own right: never outright heroic - as in the new Nolan films - but dark, dualistic, and complex.