I have been tutoring with Wyzant for about 6 months now. I started soon after finishing grad school. I appreciate the services it provides, and wish I would have known about it when I was a student.
Pros: I like that the financial information is handled through Wyzant. They ensure the money is there to pay me, and I don't have to do a thing. I have had students who short me on what they owe; some tutoring sessions take longer than expected. With Wyzant I never have to worry about that. Also, they give me greater visibility than I have been able to find anywhere else. Want ad postings get me a fraction of the exposure I get through Wyzant. And their website ensures a satisfactory experience for the student as well. Their certifications help weed out those who don't have a clue, they offer a satisfaction guarantee for the first lesson, and offer background checks on the tutors.
Cons: They're expensive. For me to make my normal rate, I have to charge an extra $10 to cover the cut Wyzant takes. Also, they limit my travel radius to 40 miles, when I would be willing to travel twice that distance to reach higher densities of students in my core subject areas.
Conclusion: Wyzant offers screened tutors at a moment's notice with a minimum of fuss. However, you pay for their services, perhaps a little more than expected.