“Opera Philadelphia has been planning this for a couple of years: Now, the O17 festival has begun, turning the city into a giant opera stage for 12 days. The company is striking a huge blow for the idea that arts organizations do better to add new, exciting things than to tread with financial caution. The festival is one of the most enjoyable additions to the fall calendar in years; it’s attracting opera fans from all over; and so far, it looks like a success.”