I have owned Rocket French for several years, but have not had the time to devote to it. I find that it quite comprehensive, so far, for conversational French. I also to Duolingo and really like it to set me straight on French grammar. One gets a lot of practice there, especially if one makes many mistakes, as I do. Also one can review to one's hears's continent. I don't know if one can actually learn conversational French with Duolingo, but it does give one the basics to experiment with French speakers or others learning the language.
However, I think that (I haven't actually tried it) one will learn conversational French more quickly with Rocket French. I cannot vouch for any other method.
I have had two semesters of French at a university. I also value that experience very highly.