Visiting the opera is often worth it's price, the staff is very service minded, both at closets and in bars. There are a number of hosts roaming the floor, ready for questions and guiding. All jackets, coats etc. must be stored in closets for a small fee. Even if there are a number of such closets, the queues can be quite long. Bring cash for fast service.
The opera hall itself is quite large, but not very spacious. It's about four stories high, having balconies on all floors, except the first one. I've found that the best seats are probably on second or third row. Having places on first row, it can be hard to hear the lyrics, since the symphonic orchestra is situated just below first row.
During the break, all available staff serves drinks and snacks, even in closets. Gaining access to toilets during the break can be a bit of a hell, since the toilet areas are quite small. It's probably best to take the elevator to the top floor, on each far side of the balcony, there are available toilets with not so long queues.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.