Gateway should be reasonably reliable, as they have the money to pile into their infrastructure and bandwidth if the service starts flagging. If you are an experienced web user then you shouldn't have any problems, especially if setting up an account merely involves setting up a dial-up networking connection. The ISP should supply help pages on its web site. If it doesn't, then don't use it. Check pitfalls .
Different companies offer different facilities.
Some support ISDN, others don't. You may get more than you asked for. You usually have to give away personal details when registering. The service is free, so perhaps you can't expect as good a service as if you were paying for it, and if things go wrong you have little legal redress from the supplier. Having said that, there is enough competition to ensure that standards remain relatively high.