It is very flexible to implement in any application with the help of any toolkit like Spring or Java. The UI is very user friendly and has all the features one needs to build secure applications. I have worked with this product for almost 3 years now. There is nothing much which can be said about it as far as its usability is concerned. In my experience, it's been easy to use and I do not find any problems related to its usability. We have developed several micro services using this, and I'd say that we are using it in almost every micro service. This ensures that there is no single point of failure in our setup.