The new iPhones come in silver, gold, space gray and the new "rose gold" (aka pink).
Apple says the phones' displays are covered by a brand-new type of glass, the strongest in the industry.
The phones also have haptic feedback -- subtle, specific vibrations -- enabled via a new spring-loaded mechanism.
The phones feature Apple's latest M9 motion co-processor, built directly into the chip.
Faster third-gen, 64-bit A9 processors run the show.
Apple says the new A9 chip is 70 percent faster than the A8 at CPU tasks, making it as powerful as a desktop's processor.
It's also 90 percent faster in delivering graphic tasks, having as much GPU power as a game console, Apple claims.
The phones have enough power to support 3D-intensive games such as the new Warhammer 40K Freeblade, which was demoed at the event.
On the back, the phones come with an all-new 12-megapixel iSight camera, packing 50 percent more pixels than those on the iPhone 6 and 6 Plus.
On the front, its FaceTime camera now has 5 megapixels.
The phones have a new custom display chip that makes the displays three times brighter. It can also be used as a TrueTone flash using the phones' Retina screen to support the FaceTime camera.
They also have the new second-generation TouchID sensor, which is significantly faster than the earlier version. You won't need to rest your finger on it for nearly as long.
Moving from Android? You can easily find iOS apps based on the apps you're accustomed to on your old phone.
The new phones support faster 4G LTE cellular speeds, now up to 300Mbps (depending on your carrier, of course).
The iPhone 6S and 6S Plus come with a variety of accessories.
And cases in many colors.
To sum up, the new phones have the following new features: 3D Touch, 7000-series aluminum casing, the strongest-ever cover glass, a 64-bit A9 chip with M9 motion co-processor, second-gen Touch ID, faster 4G LTE and Wi-Fi, 12-megapixel iSight camera, 4K video support, a 5-megapixel FaceTime HD camera with Retina Flash and Live Photos.