A unified, Apple-designed HomeKit app has been desired by HomeKit users since HomeKit first debuted, and it appears Apple is planning to introduce such an app in the near future, perhaps in iOS 10.
The hint on Apple's HomeKit plans comes from an Amazon reviewer who works in the marketing department at Apple. The name of the reviewer coincides with the LinkedIn profile of an alleged marketing employee at Apple, and we have confirmed that the Amazon review was indeed created by the Apple employee.
As I work in marketing for Apple, we test many Smart Home devices, especially for iOS HomeKit integration. [...]
Some advice, there are many third party applications, most free, that offer more control and customization(s) with many Smart Home devices. "Yonomi" is a free app that I often use, "Home" is another which cost $14.99. Both offer support for many devices with more added daily (including Amazon "Echo"). The next version of iOS due this fall will have a standalone "HomeKit" app as well.
While we verified the source of the information, there's always a chance that Apple's plans could change ahead of the release of iOS 10. There have been several past rumors suggesting Apple would debut a public HomeKit app, but such an app has not materialized even though Apple has long used a HomeKit app internally.
A cohesive, Apple-branded HomeKit app would go a long way towards improving the HomeKit experience. At the current time, HomeKit users with multiple products must use several different product apps, many of which offer different features, or rely on third-party apps.
Update: Further research on the alleged Apple employee who wrote the review suggests the information leaked about an upcoming HomeKit app in iOS 10 was a hoax. It is not clear if and when Apple will release a standalone HomeKit app.