If it is difficult for you to formulate at once what the article will be about, start writing it from the main part, and add the introduction at the end, when the finished text will be before your eyes. The best is to visit the performance several times to test your first impression.
Mention at least one or two issues the play has or has not addressed. Apply for help at WriteMyEssayOnline. Do they offer evidence to support their opinions? Leading topics.
Breaches in logic, messy narration, a weak or trivial main idea, silly scenes which do not contribute to the plot—this is what definitely makes it worse. If it is, what makes it good? Taking notes in a theater might be a hard task; most likely, you will not be able to write much down, and typing in your phone would take too much time and its light would distract other people.
If you previously saw this performance with the actors of another theater, in the production of another director and other performers, then compare the performances.
Choose a modern play for a start, not a classical one; classics are harder to evaluate, because they have been performed for decades or even centuries, and the performance will be most likely perfected.
There are as many ways to write a review as there are personal responses to any production. Start your review with an attention grabber that will make the reader believe that your review is worth reading.