It was a favorite haunt of Matisse and/or Picasso, not Monet, as I recall...
I went to the show 8 years ago in a jet-lagged haze and I largely concur with what Ed says. It was a nice, intimate show (I think the audience was under 100 people) where they sang several folk songs. I don't remember the stand-up parts, but being jet-lagged and not speaking French probably took care of that.
Probably would not go back, but it was definitely nice the first time. I don't recall them serving any food there, but there are plenty of nearby options.
If it's performing in your area, see the play "Picasso at the Lapin Agile" sometime or check it out from the library. Decent (if semi-fictitious) overview of the context behind the place, and a fantastic script as well.