High frame rate video has been a hot topic in the past few years driven by a strong need in the entertainment and gaming industry. Nevertheless, progress on perceptual quality assessment of high frame rate video remains limited, making it difficult to evaluate the exact perceptual gain by switching from low to high frame rates. In this work, we first conduct a subjective quality assessment experiment on a database that contains videos compressed at different frame rates, quantization levels and spatial resolutions. We then carry out a series of analysis on the subjective data to investigate the impact of frame rate on perceived video quality and its interplay with quantization level, spatial resolution, spatial complexity, and motion complexity. We observe that perceived video quality generally increases with frame rate, but the gain saturates at high rates. Such gain also depends on the interactions between quantization level, spatial resolution, and spatial and motion complexities...