In the US, rather and quite are very strong intensifiers, often meaning very, totally, or really. Rather tends to be used with an adjective / adverb that is considered undesirable, and quite with an adjective / adverb that is considered to be desirable although this rule is not strict. "Quite beautiful / quite gorgeous, rather ugly / rather hideous. For the British use of rather and quite, Americans usually say pretty (oddly enough).