How do you measure yourself? How do you know your release is of acceptable quality? You've found a lot of bugs, and you've fixed a lot of bugs. You have a set of great new features, and you've done all sorts of interesting security and usability testing. It's a great release! Or is it?
Your release is of sufficient quality if your customers are sufficiently happy.
The real trick here is to define "sufficient". You could have hundreds or thousands of bugs in the product, and if your customers don't hit them or don't mind them (or think a bug is a feature!), then it's still a release of acceptable quality. You could have a total of 5 bugs, but if your customers hit them a lot and they're bad, then this is not a release of sufficient quality.
So if you want to know how you as an engineering (and requirements gathering and sales) team are doing, ask your customers. They're the ultimate arbiters.