The access to Netflix original series with a Netflix instant account - only $9 a month at the time of writing - is cheaper than access to HBO or Showtime alone. Netflix's streaming model also does not contain the normal restrictions that scheduled programming has, and with the success of House of Cards, Orange is the New Black, and the revived Arrested Development, they are matching the success and soon to be outpacing the major networks.
Yes, the series on Netflix make the account worth it because they are some of the most popular shows on any platform. Netflix is inexpensive and the series are a plus. You have basically every movie and every TV show you want to see, including the Netflix original series. Netflix would be good with just movies, but the series make it great.
I do think that in addition to having Netflix series at your fingertips, a Netflix account is worth it. Not only do you have access to numerous movies and non-Netflix television shows, now you also have access to the quality original shows that Netflix has rolled out. It's definitely worth it to have an account.
Television programmes such as Breaking Bad, Orange is the New Black and House of Cards are considered to be pioneering, creative and intelligent programming which have made a significant impact on television studies. The Netflix subscription isn't expensive and it is the only place to see these critically acclaimed shows.