Apart from access control systems, it hardly has any good uses in the real world as a pen-testing device. If it was a pocket carry, true SDR, capable of recording RF signals as I/Q, performing actions on them, replaying them, etc, it would have justified its cost. But, with a limited set of modulations supported by the used RF chips, it is more like a toy for hacker wanna-be teenagers than a serious tool.
An investment in something like HackRF+PortaPack clone is far better, IMHO.