Yes, I had joined the KWA more than a year ago. I stayed for 3 months and then cancelled the membership. At the time i joined they had the guest post module, the keyword analyzer, the forum, and a few other tools which I believe don't exist now. I'm sure they've made improvements after all this time.
At the time I joined I found it to be a good introduction to what keywords were all about, and using them within your site content. They also covered backlinking (which has changed drastically since then), and the forum was helpful in answering some questions.
Why did I opt-out? I noticed at the time that the forum was drying up. More and more questions I asked were unanswered. The guest post module was less effective for backlinks than I had hoped. Some of the online seminars were being cancelled, and/or the material was getting repetitive.
But, overall the first few months were informative and it set the foundation for the next steps - SEO.