As of Release 16.01 for the ArubaOS Switches (2920 is one of them) the benefits and integration with the entire Aruba portfolio is coming into play , as stated before, support for ClearPass is part of this release, which means , that Change of authorization (CoA) and Captive Portal are fully supported.
If you are using other Aruba product on your network there are a few other cool features that might come handy. Rouge AP Detection, Set PoE priority, Auto Add VLAN - all of these are MAS Features that are now supported by the 2920. other features incluse AirWave support - Zero-touch provisioing, firmware upgrade and Template based configuration.