Anita Gates in The New York Times reviews "Strings" that may be somewhat analogous to "Copenhagen" although it is probably not as good. They talk about quantum mechanics and string theory most of the time while a woman shared by two men is isomorphic to an electron shared by two atoms, the review says. ;-)
Adam Klasfeld offers something that I would call a positive review in TheaterMania.
Where? 78th Street Theater Lab, New York City.
Because this short article is about fiction, let me also mention a positive review of the book "Please, Mr Einstein" in San Francisco Chronicle. Albert Einstein is apparently still alive and he works on string theory, among other subjects, in an unspecified European city.