Comments on NIST’s proposal to approve FFX
What's on the NIST web site seems to say everything that needs to be said:
On June 9, 2011, NIST announced a period of public comment on a proposal to approve two schemes of the FFX framework for format preserving encryption: FFX[radix] and VAES3. The public comments that NIST received in response to this request are collected here.
Oddly enough, the comments are all very positive. In situations like these you usually get negative comments by vendors who don't have an interest in the technology which give either weak or obscure technical reasons why a particular proposal is bad.