There was a brief time where I thought this was possibly the worst song John Mayer ever wrote (until I heard his latest stuff). This song grew on me over time. There is something about it that is timeless and easily likeable - but I used to sing it in a "parody" voice because I thought the song was ridiculous.
Then one day I pulled up the backing track in C#m and the song made more sense to me. John is a student of the blues and even it his most pop productions he always seems to tip his hat to the blues. As a listener the song has grown on me. I thought it was a bit of a dirge - but somethings changed with this one.