I've been using this site for a little over a year. I still question whether it helps or if it is only turning someone into a robot. I totally believe in exercising the brain, but that can be done in many ways and most likely for free. I was stupid enough to join, because I thought it would be easy and then I would do it. This turned out to be true, I was using it at least 6 days a week for about a year. Sometimes it just seemed repetitious. There was one game which I reached their top level and I would lose points for playing it as it was part of my training course for the day, which were many - I sent in a question on it and several days later received a response which pretty much said nothing. Hmm,,,, I guess they aren't really studying their stats.
Well, the real turn off is the customer service. You open a request, they hope you forget about it or it gets resolved on it's own, you then comment on the open request asking if anyone works there and finally an answer comes that provides absolutely nothing.