Bluetooth Low Energy (BLE) is the short-range, single-hop protocol of choice for the edge of the IoT. Despite its growing significance for phone-to-peripheral communication, BLE's smartphone system performance characteristics are not well understood. As others, we experienced mixed erratic performance results in our BLE based smartphone-centric applications. In these applications, developers can only access low-level functionalities through multiple layers of OS and hardware abstractions. We propose an experimental framework for such systems, with which we perform experiments on a variety of modern smartphones. Our evaluation characterizes existing devices and gives new insight about peripheral parameters settings. We show that BLE performances vary significantly in non-trivial ways, depending on SoC and OS with a vast impact on applications.