I think that proper criticism includes a summary of the music. Which part is good? Which part is bad? Which part should be changed, and how? Perhaps why as well.
Normally criticism given this way will be received with an open mind, although the receiver may not react to the criticism. It is up to him what he decides to do.
You can't say that only techno is music, or that only classical is true music, or that jazz is the only kind of music that is supposed to exist, or that everybody should listen to fusion. Different people like it differently.
Experimentation and change is good, yes. It lets the brain create more ways of expressing ourselves through music. Music usually is a form of communication, and some other times expression. Or we can say that music is for enjoyment, for other purposes as well.
If we can communicate, express, enjoy, and fulfil our purposes and perhaps that of some others through the music that we create, that piece of music would be considered successful already. How big the success, that, is another matter.