Project Ara is a platform still in development - not yet ready for the consumer market. There are still parts of the phone that are works in progress and/or require more research before final market readiness. Security is one issue that remains in the Ara project for now - battery life is another. One thing - actually, several parts - that are actually confirmed and working are all in physical hardware - the Endo base of the phone and Module pieces. How do you interchange them? How are these Modules mounted on the base?