That topic have been covered in so many other random threads out there but essentially, some people are going off by price, it is roughly mid fi there, others go by how many other stuff out there which is better (but still very similar sounding) eg HE500 is would say (comfort aside).
Is it bad? no the HD650 is still my favourite. Did the sound suddenly get worse? no it's just that some of the newer stuff sound marginally better.
Point is, buy the headphone and don't worry so much about where it fits on the totem pole