Often seen as an afterthought to the melody, the use of harmony can actually be the most compelling part to a piece of music.  While melody has always been a constant and dependable part of music, harmony has taken more twists and turns throughout history.  Harmony has grown and adapted more than any other element of music (although timbre may surpass it soon), and can truly be the gateway into the mind of the musician.  It grew in complexity for centuries, up until the last 100 years or so when harmony has either been completely ignored or made extremely simple.  In any case, harmony is a measurable element in music, and one that I will take into great consideration.
Notice that I am rating the music based on harmonic creativity, not harmonic complexity.  A piece of music may have a rudimentary three chord progression, but if it is used in a way that enhances the musical experience, or is paired with a unique and riveting harmonic rhythm, it will receive a high rating.  For example, even if the same four chords I, V, vi, IV are consistently used in a row, they could constantly change how they are voiced and also change where they stop at the end of phrases to vary the cadences.  These are creative ways to use the harmony.  On the other side of the argument, many musicians also use the same three or four chords over and over again do not yield much creativity and therefore leave the listener without any harmonic pleasure. A piece could also be harmonically complex without much creativity.  Songs may use very complex chords in relation to functional harmony, even masking the true key they are in by use of many borrowed chords.  What this harmony can lack, though, is a sense of progression and togetherness.  It may just be a sequence of non-related chords thrown together, and while that may serve a melodic or timbral purpose, it is not harmonically creative.
Since my reviews will span across many different stylistic approaches, what was harmonically creative for one song may not be for another.  Depending on the musician’s intent or overall delivery, certain aspects of harmony may be more creative than others.  I will rate the harmonic creativity of the music based on the overall technicalities the musician could realistically operate with.  This means that I will not downgrade a simple pop song simply on the basis that it does not include a German +6 chord.  I am also not going to rate a more sophisticated song any higher just because it includes +6, Neapolitan, or diminished 7th chords.  In order for music to be considered great, it must use harmonic language in a creative way that enhances the character of the piece, regardless of what language is being used.
This category is scored out of 50 points.