It's interestng, as I too am not completely comfortable with MM either. I used it to retreive all my music that had been hoovered up by iTunes when my daughter helped herself!
In reality, I find WMP much simpler to use, but I suspect I am stuck with MM now. I feel that it is a program designed to do everything, but being a bit of a simpleton, and not a purist, I don't want to be able to manipulate my tracks, rate them, score them or rename them! However, I am currently recording all my vinyl so MM is probably the best way of doing this (using Audacity - highly recommend it!)