The Collaborative International Dictionary of English v.0.48:

Appreciativeness \Ap*pre"ci*a*tive*ness\, n.
   The quality of being appreciative; quick recognition of
   excellence.
   [1913 Webster]

WordNet (r) 3.0 (2006):

appreciativeness
    n 1: warm friendly feelings of gratitude [syn: gratefulness,
         thankfulness, appreciativeness]