The new iPhone 6s and 6s Plus are 90% faster in terms of graphics and 70% faster in terms of CPU power compared to the previous iPhone 6 & iPhone 6 Plus.
The new 12MP rear-facing camera and 5MP front-facing camera are huge upgrades over the 8MP/1.2MP cameras of the iPhone 6, iPhone 5s and iPhone 5, iPhone 4s and iPhone 4. Seriously, this is the FIRST time Apple has actually upgraded the camera hardware in like 5 years.
Very importantly also, the battery life is rumored to be about 2X that of the iPhone 6.
I think this represents the biggest hardware upgrade that Apple has ever done. The iPhone 6 was just a form factor change from the iPhone 5s. The iPhone 6s is a HUGE upgrade over the iPhone 6 in terms of hardware.
New rose gold color!
Pricing in the US:
The specs themselves should be taken with a grain of salt. For example, the 12MP camera on the new iPhone 6s and 6s Plus, despite having a relatively lower resolution compared to most new phones, will be one of the best cameras on the market, 100%. To be honest, 16MP is probably the maximum MP count anyone would need. >16MP is overkill and many phone cameras with high MP counts usually have poor sensor quality.
Currently, the Galaxy S6/S6 Edge/Note 5/S6 Edge+ have the best cameras in the smartphone market to date. The iPhone 6s and 6s Plus will probably come near or match the image quality of these cameras.
Also, the 2K Super AMOLED displays of the Galaxy S6/S6 Edge/Note 5/Galaxy S6 Edge+ lineup are still the best displays on the market according to DisplayMate. Not sure if the iPhone 6s and 6s Plus can beat them, and most likely they can't because the iPhone 6s and 6s Plus lack the 2K resolution. However, they will undoubtedly be of much higher quality compared to the last generation iPhone 6 and 6 Plus.
One thing is for sure though, the iPhone 6s and 6s Plus will be the smoothest phones (in terms of speed and performance) on the market. iOS has Android beat when it comes to software optimization, at least for now. The iPhone 6 and 6 Plus have some lag that I noticed, especially with Google Maps and Internet web browsing. The iPhone 6s and 6s Plus should solve these issues with the superior A9 processor which utilizes 14nm architecture. The new DDR4 RAM modules will also be a huge boost to bootup speeds, app launch speeds and overall performance.
I'll update this post later when I get more time.