One problem I've always had with this play/film
Felix and Oscar are supposed to be long time, close friends (I think at one point Oscar refers to him as his "oldest and dearest friend) and yet Oscar seems taken completely by surprise by all of Felix's habits, idiosyncrasies, allergies, etc. Also, for such close friends, they each seem to have no clue about the other's marital issues, etc.
For that matter, it's basically impossible for me to imagine a fastidious guy like Felix playing poker in an incredibly messy apartment with the rest of their buddies (remember we never actually see Felix play a hand). Felix, as he's written, really doesn't fit into this group at all.
It probably would have worked better and made more sense if they were just passing acquaintances.