That is not to say that it does not have its flaws. Scheduling hearings is often a mess, too often arbitrators don't want to make decisions, and the certainty of evidentiary rulings is iffy, at best.
I have represented parties in other forums, notably the NYSE when it was conducting arbitrations and some of the commodity exchanges. Those all have similar issues.
I have also represented parties in AAA arbitrations, both in the securities and non-securities industries. While the experience at AAA is much smoother than FINRA, there is a significant cost difference. Arbitrations at AAA can cost thousands of dollar more than a FINRA arbitration
I have never conducted a hearing through JAMS, but Alan Wolper, of Ulmer & Berne has written a blog post regarding his recent experience at JAMS. He points out the problems with FINRA arbitration that do not exist at JAMS and gives his JAMS experience a positive review.
AAA and JAMS are more expensive, and sometimes significantly more expensive. However, you often get what you pay for.
Alan's post is at JDSupra.