Public Citizen says:

The findings provide a snapshot of how arbitration traps consumers throughout the country in unfair, secret proceedings where for-profit arbitrators make the rules.

Here's National Arbitration Forum's response:

Consumer outcomes in arbitration are the same as in court. Every published study and all empirical data indicate consumers prevail at a rate that is greater than or equal to litigation, where similar subject matter is at issue.

Earlier this year, I wrote that the state Supreme Court decision ruled against the former Cingular Wireless, now AT&T, saying it couldn't enforce a waiver in contracts that prohibits customers from pursuing a class action.