A country/blues singer at best

Reviewing Norah Jones's "Live in 2004" DVD, Phil Stafford (Review, Weekend Australian, 15-16/1/05) says that "Jones was wrongly tagged at the outset as a jazz musician, and this outing merely confirms her as an engaging country/blues singer, at best".

At best! Is Stafford trying to tell us that country/blues is an inferior genre of music?