Complex sentence: This is the criteria which each individual has as a metric for what constitutes music's aesthetic value and could be comprised of varying personal preferences as to what makes the song aesthetically pleasing such as the message conveyed, skill presented or novelty of style/idea.
Split into simpler sentences: This is the criteria which each individual has as a metric for what constitutes music's aesthetic value. This can be comprised of a number of varying personal preferences as to what makes the song aesthetically pleasing, such as the message conveyed, skill presented or novelty of style/idea.