Yes, TAK/ATAK is very useful. Have used it for a few years now. As well as some of the military Medical related Android applications.
Getting others on board for its use though, at least for my employer and organizations is a little harder. The only good part is they all like looking like forward air controllers with cell phones in overly expensive chest mounts that always seem to break when they check their phone/applications (hinges breaking, routing of battery cables [conformal batteries stowed in plate carrier pouches] and related damage, and then antennas sticking up on either side - glad I retired from that world a decade ago).
But, interoperability and getting a copy of the NIFOG into end users hands has helped, mostly with fire fighters - they tend to see the necessity of communicating effectively with other organization (mostly other fire elements) at least. Security/public safety types just want to "look cool" as some of them have stated in my case (while they lose new radios - to be found on the side of the highway by other public safety elements, at least we know we can transmit inhibit or stun a radio).