For what it's worth, my $0.02
Growing up as a Gen (insert late in alphebet letter here) youth with access to computers, my take will likely be different than yours.
I think at some level there is a primary issue of trust and parental responsibility involved. This software, to me, is a work around for proper parental involvement in your child's activities. If your child is not trustworthy of having access to a computer without mis-behaving, then they should only be allowed to access a computer when supervised. If you don't trust the child already, then no program in the world can stop them misbehaving if they have the access to a working PC. Even at 13, I could have gotten around your software any day of the week if I was alone with a computer. Even today, I could go a friend's house, burn a CD that's a boot-able web-browsing OS, and have all the mischief I wanted without oversight. The problem here is that not only would I be mis-behaving, but you would be false secure with your monitoring software only showing my legitimate activities.
Don't mis-understand me. I'm not questioning your parenting. I just think software of this nature is not the best way to handle the situation. You'll end up with a marginal computer, and an unrealistic view of reality.
Of course if your teenager has absolutely no computer talent, and you really just want to spy on the back end rather than directly address the issues, it looks like a good program.