It is a number game. It is about the number of installs, the number of countries, the number of hotel chains & standalone hotels
making Opera PMS their standard property management system. I knew that it was over 35,000 installs all over the world a few years back,
though I don't have the exact numbers now.
Accor, Best Western, Corinthia, Fairmont, Four Seasons, Marriott, Shangri La, IHG or Intercontinental Group, Hyatt, Kempinski, Whydham are some of the leading hotel chains that use the Opera. It is just 2 of the leading hotel chains, Hilton & Movenpick don’t use Opera as their standard property management system, I can think of or this link might have more info.
While it is the number that interests hotel software providers to invest in integration, for a hotel or a hotel chain, by virtue being a partner offering a ton of functionalities to solve everyday issues, long-standing trust that began with the WOW features of Fidelio, the predecessor of Opera of ugly DOS days with virtually no competition, Opera seems the lifelong adaptive PMS.
There is another important trick that has been putting Opera in front of others; its interoperability with a variety of other indispensable solution providers in the industry, when APIs were never heard of. The telephoning, door locking, accounting, point of sales, in-room entertainments, store systems or BMS, probably Opera has the widest coverage in integration. As of this writing, there are over 2000 certified vendors in the 'certified list', and the number grows.
However, things changed, there was a time when only the well-established companies came up with products that hotels recognized & used, so investing any amount of money on integrating their products with a leading PMS was making sure they double the ROI.
Today, there are thousands of startups coming up with better ideas to solve more problems than before. Unfortunately, they think twice if they have to invest in integration with a PMS at a stage when they're not sure if they will be accepted in the industry where the traditional decision making still dominates.