Simplicity of use. Popularity makes it easy to find opponents during the whole day. Pager feature is more versatile. Really eats up a CPU's resources and modem speed. Overcrowded at peaks of service use.
People tend to be less supervised.
Porn addled at times. Crashes my poor computer. Better admin system, meaning more people can be helped. Dedicated chat lobby. Registration doesn't stick a big honking icon on your profile.