Compare the cost of e-mail sending and receiving and browsing time. Some services are better deals in one area, others are better in another. This is an area of high competition and constant change, so be sure to have a good list of questions before you decide which service to subscribe to. The content submitted by the publications and services is generally high, since they are selling this as a commercial product. The organization is thoughtful and consistent.
Quality standards are more rigorous.
These services are like mini-World Wide Webs. Be sure you know what you can, and can't, do in the service. If all you want is Internet accessibility, there are much less expensive options available. Most of the services have certain areas available at no extra charge, but if you click over to another area you are charged for connect time. Read your charge sheets carefully.