I just finished watching this movie, it was the first Jerry Lewis film I've seen, and I'm already a fan of this comic genius. Three On A Couch is full of gags from start to finish, constantly keeping the audience laughing with Jerry Lewis' character's attempts to make three women think he's three separate people. Jerry Lewis shows his talent as a comedic actor as he plays all those characters perfectly, but also awkwardly as though he's nervous that he might get found out. And yet the awkwardness is so subtle that it's believable that the ladies don't think something's up. He's also very deadpan in this movie, and at the same time high energy in his gags, much like Charlie Chaplin. So, bravo Jerry Lewis, you put on one heck of a performance.
Although I will admit that some of the jokes didn't work. Some of them went on just a tad too long. Although they don't hurt the movie much. Also one thing I thought the movie should've done was make the three women more developed characters instead of just one-dimensional straight-men. Only one of them showed a personality (the athletic one), the others just seemed to have personalities described but not shown.
Judging by the low score and the fact that it was featured in a book called Fifty Worst Movies (or something like that), I'm guessing this is one of Jerry Lewis' lesser movies. I haven't seen any of his other films so I can't say if Jerry Lewis fans will enjoy this, but I'd definitely recommend it to people who want to watch a really funny movie.