Motivated by rapidly expanding deployment of 5G services, we carry out an in-depth study to understand how 5G impacts application performance and energy efficiency. We examine the effects of 5G deployment strategies such as Non-Standalone (NSA) 5G and Standalone (SA), radio bands and protocol specific properties (e.g., RRC state transitions and power profiles) on performance and power usage experienced by user equipment (smart phones) and applications running on them. Unlike previous studies, we focus on both 5G mmWave – which provides significantly higher throughput than 4G LTE – and low-band radio (with more comparable throughput with 4G LTE). Our work answers the key questions of how to best utilize 5G for common applications such as video streaming and web browsing, and aid intelligent throughput-power trade-offs.