This paper gives an overview of the fundamentals of liquid micromixing in rotating packed beds (RPBs) and delivers an assessment of RPB micromixing based on the Villermaux-Dushman protocol. This analysis is structured into four parts. In the first two parts, general trends for the operation and design of RPBs to ensure fast micromixing are derived. For this purpose, the influence of operational parameters, such as rotational speed, liquid flow rate, volumetric ratio, and viscosity, on micromixing is investigated. Afterward, design parameters, such as inner packing radius, outer packing radius, and packing type, are addressed. Additionally, rotational speed and inner packing radius are for the first time presented and compared based on the corresponding tangential velocities. This comparison reveals the particular influence of the liquid distribution and the impingement zone on mixing in RPBs. In the third part, model parameters, such as the micromixing time parameter in the incorporation model, are discussed. Finally, micromixing results for RPBs with structured packing are compared to results for non-structured RPBs and other continuous mixing devices, such as spinning disc reactors (SDRs), high shear mixers (HSMs), and T-mixers.