Pros
It has all the pros of tutoring (flexible, good pay, selection of clients) but you also get to advertise your services in a manner that is more appealing to clients. It is way better than an ad posted on craigslist or kijiji.
It also helps when an issue arises. I had a set first session with a client. I got there and the client never showed up. The management team resolved the issue for me. The policy was respected, I was paid which never would have happened if I was on my own.
At first the 35% that they take seems to be a con. However, over time it is worth it. Plus, it decreases with hours worked.
Cons
I really can't think of any downside.