1) The reports of those who checked the correctness of the paper can be viewed here.
2) A shorter proof of the alternating sign matrix conjecture, using the formula of Izergin and Korepin, was given by Greg Kuperberg ``Another proof of the alternating sign matrix conjecture'' (file asm.ps.gz, to appear in Inter. Math. Res. Notes).
3) Using Kuperberg's method of proof, and in addition orthogonal polynomials, q-calculus, and EKHAD, I found a proof of the refined, stronger, version of the ASM conj., also conjectured by Mills, Robbins, and Rumsey, and mentioned in my paper (Stanley's Baker's dozen no. 3). It is given in
Proof of the refined alternating sign matrix conjecture (submitted)