They are also the sole Cable provider in Rhode Island.
Besides Rhode Island they do not have a big footprint and are 3rd largest preceded by Comcast and Time Warner.
Like all service monopolies, customer service is not a top priority. They are known to piss many people off and chase them out to Satellite TV since each cable company has a monopoly in the areas they serve.
Cox also offers Internet and Phone, and will give you the triple play offer which is Cable, Internet, and phone for $100. Otherwise though, their services are expensive. It is not unheard of to pay for $100 on digital cable alone with Cox after taxes and rental fees. The company goes as far as charging a rental fee for the REMOTE.
As far as Cox internet goes, for the most part, it is competitive with DSL. Most of their packages are $3 to $5 more or less than DSL's equivalent. Service is not the best and you will always find yourself stressing when calling the customer service line, for all of Cox services.