Took a tour of the Opera House, and at $28/per person, nothing out of the ordinary, but worthwhile in the sense that you have access to see all of the theaters and balconies that you wouldn't otherwise. Even if you were to see a performance, you wouldn't necessarily get to walk around everywhere. The Opera House history is pretty amazing/interesting and the views below and above are irreplicable. Depending on the number of photos you are planning on taking, shouldn't take more than a couple hours to see the tour and explore on your own. Free Wi-Fi is great for people who have no international phone access!
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.