Bruce Stokes gives his take on the deal in his latest National Journal column (it's unclear who is he is talking about with the capital L Left, since I know of no progressive group that has endorsed the deal, but his point about the merits is worth reading):
Conservatives who complain that the deal was a victory for organized labor that will open the floodgates to protectionism have it all wrong. The deal demonstrates the unions' weakness, not their strength. The Left expended enormous political capital to achieve what is largely a symbolic victory.
Under the Hill-White House deal, a foreign government that refuses to allow its workers to organize, to bargain collectively, and to maintain other minimum labor standards will make itself vulnerable to the reimposition of tariffs. Labor has long sought to embed this fundamental principle in trade law. But, at best, this achievement will empower Peruvian or Panamanian workers to begin a generation-long struggle to improve their wages and working conditions.
And it is unlikely that if a country violates the labor-rights provisions it will be subject to any quick penalties. The process for the reimposition of tariffs to enforce labor rights, under this deal, is modeled on similar language in the free-trade agreement with Jordan. But that provision has never been tested. And, as some on the left have already pointed out, it is unlikely that the anti-union Bush administration will agree to bring a case against the abuse of labor.