The main thing I like is that it's extremely easy to use for all users - not only radiologists but also other physicians involved in patient care (e.g., nurses).
It makes collaboration so much easier! There are some things we would love to see improved upon such as more intuitive navigation through modules/pages of content; however this has been addressed by updates recently which have made navigating the system even better than before. We've used CMRS since 2015 and continue using them today because they have helped us provide quality education material to our residents throughout their training program.