Rope is infamous for the 12 minute cuts that take place throughout the film, that is not a single cut is taken until the reel finished. It's the type of movie that should and probably is shown in cinema classes. Some have criticised the movie as self indulgent, but the film ends up being a good movie through an excellent script and very good acting, which pulls it through in the end.
Though Farley Granger doesn't impress here, he is by far upstaged by the manical John Dall. The support is strong too- think James Stewart and Cedric Hardwicke.
An otherwise excellent film, forget the naysayers.