Personally think if you're wanting to find classmates Facebook is a better solution.
I agree. I've had more meaningful interaction with high school classmates from Facebook than from Classmates.com.
I suspect Classmates.com is struggling to survive. They normally charge $39 for an annual membership. You can have limited access for free but that really doesn't give you much of a way to communicate with others.
Years ago, before Facebook evolved into the dominate social networking site, I managed to get in touch, using a free Classmates.com account, with someone who was in the U.S. Air Force and stationed in South Korea at the same time as me. That communication did not really take place within the Classmates.com website; it merely provided a way for me to get some email contact going outside of Classmates.com.
In August 2010, Classmates.com had a promotional subscription offer in effect. It was an annual subscription for $9.95. I tried it but really didn't get much satisfaction from it. The experience just confirmed that Facebook is a better way to get in touch with old friends.