I am of two minds about this series. The first is that the cast is so stellar that it is a must watch program. Jane Fonda, Lily Tomlin, Martin Sheen, and Sam Waterston all have had illustrious film and television careers and are likable characters. They are also actors who are over 70 years old playing characters in that age range, which is an anomaly in modern entertainment (they all look great for their age, but not insanely great, so it is believable and not depressing). The second is that the show just really does not live up to the hopes you might have for it. The dialogue is stilted and falls flat on more occasions than not. That said, I would recommend it.
The story is that Grace was married to Robert and Frankie was married to Sol. Sol and Robert have been friends and business partners for decades, but Grace and Frankie were more like water and oil. Grace is all about elegance and appearances and Frankie is touchy feely artist type. The couple's friendship was driven by the husbands and the wives tolerated each other. Then Sol and Robert reveal that they have been having a romantic relationship for twenty years and now they want to live as an openly gay couple and get married. Neither Frankie nor Grace want to remain in their marital homes so they both move to a beach house that the couples shared. Under these circumstances the four of them share two abodes, just for different reasons. The contrast between the two men trying to live as openly gay men and the two women trying to navigate the waters of being single and dating in their seventies is a good comic environment, but the execution is less than perfect. I hope for a better second season.