Accurate and low-power indoor localization is becoming more and more of a necessity to empower novel consumer and industrial applications. In this field, the most promising technology is based on Ultra-Wideband (UWB) modulation; however, current UWB positioning systems do not reach centimeter accuracy in general deployments due to multi-path and nonisotropic antennas, still necessitating several fixed anchors to estimate an object's position in space. This paper presents an in-depth study and assessment of Angle of Arrival (AoA) UWB measurements using a compact, low-power solution integrating a novel commercial module with Phase Difference of Arrival (PDoA) estimation as integrated feature. Results demonstrate the possibility of reaching centimeter distance precision and 2.4°average angular accuracy in many operative conditions, e.g., in a 90°range around the center. Moreover, integrating the channel impulse response, the phase differential of arrival, and the point-to-point distance, an error correction model is discussed to compensate for reflections, multi-paths, and frontback ambiguity.