This subjective question will undoubtedly be answered differently by every reader. A helpful way of approaching your assignment would be to reread the play, taking notes along the way regarding opinions, reactions, or questions that come to mind.
Here are a few questions to help begin the thought process: Do you feel the play is relevant and interesting, even though the wording and telephone system are clearly antiquated? Do you think the foreshadowing of the murder location was specific enough to clue the average reader (or audience member) in to the imminent demise of Mrs. Stevenson? Do you think the play could be updated to incorporate modern technology, or is the idea of crossed wires too far-fetched in this era of cell phones? This question is solely about you and your thoughts about the play, so consider your reactions and have fun with your response!
I personally enjoyed the script and would love to watch the old movie version to see the action play out. I found the story riveting and creepy, akin to something Hitchcock might have directed, and I enjoyed witnessing Mrs. Stevenson's rising anxiety, which seemed foolish to everyone she spoke with on the phone but turned out to be merited. I think the futility of witnessing the plans for one's own murder and being powerless to prevent it is a fascinating, riveting idea for a work of fiction.