is "waiting for Godot" a successful play ?

I would say it is successful. Waiting for Godot qualifies as one of Samuel Beckett's most famous works and perhaps the most recognized example of the theatre of the absurd. Originally written in French in 1948, Beckett personally translated the play into English. The world premiere was held on January 5, 1953, in the Left Bank Theater of Babylon in Paris. The play's reputation spread slowly through word of mouth and it soon became quite famous. Other productions around the world rapidly followed. The play initially failed in the United States, likely as a result of being misbilled as "the laugh of four continents." A subsequent production in New York City was more carefully advertised and garnered much more success.

At first when the play was presented, people failed to understand and they demanded their money back.but slowly after few presentations viewers understood the play.in this context Samuel Beckett made them to think and understood the play. So we can call it as a successful play.