Teatro alla Scala is arguably the best opera house...

Teatro alla Scala is arguably the best opera house in the world, considering the overall quality of its performances. The singers are always from the top tier in the world, while productions are extremely tasteful and elegant, with nothing of the extremes of the German style, and less extravagant than in Paris. An opera at La Scala is a guarantee of an unforgettable performance, while a ballet is much less so - while the costumes are lavish, the dancing itself surprisingly leaves much to be desired and firmly yields to Paris. La Scala is an opera theater first and foremost.
Tickets are very expensive compared to Swiss or German opera houses, while still a better value than the New York City Metropolitan Opera. They are difficult to buy as the theater's website does not work well.
La Scala is not a theater with a democratic tradition, so if your ticket is not in the orchestra and other two privileged tiers, you will not be allowed to the beautiful foyer; ticket holders are thus segregated according to their seats.
And if you managed to buy only such a ticket at the higher tiers/balconies/galleria, be aware that there is only one small elevator, an a waiting time can be long.
The air conditioning is quite weak compared to the American standards, but much stronger than in Germany or Switzerland. Opera Bastille has a much better AC. Seats in the cheaper category (balcony, 70 euro) are very small and the public sit tight. The inside temperature in the beginning of June was about 24 degrees Celsius at the galleria. However the orchestra is not much better, but the comfortable wide seat makes a difference. Not much can be seen from the second/third row seats in the side boxes, and from the second and further rows at the galleria.
Overall being at La Scala at an opera is a pampering experience.