The Collaborative International Dictionary of English v.0.48:

Reviewer \Re*view"er\, n.
   One who reviews or reexamines; an inspector; one who examines
   publications critically, and publishes his opinion upon their
   merits; a professional critic of books.
   [1913 Webster]

WordNet (r) 3.0 (2006):

reviewer
    n 1: someone who reads manuscripts and judges their suitability
         for publication [syn: reviewer, referee, reader]
    2: a writer who reports and analyzes events of the day [syn:
       commentator, reviewer]