Just three days after its release, Apple had already sold 4 million of its newest touch-screen smartphones.
Consumer Reports found the camera on the iPhone 4S is one of the notable improvements over the iPhone 4. The new camera was upgraded from five to eight megapixels and the results are impressive.
"The camera is significantly better and it's especially good at taking pictures under low-light conditions, or when there's lots of sun and shadow," said Mike Gikas of Consumer Reports.
Consumer Reports found the iPhone 4S is faster than the iPhone 4 - as promised - particularly when launching apps and Web pages.
As far as the Siri interface, which allows users to make voice commands, Consumer Reports says the voice-activated control is remarkably good at understanding and executing requests.
Consumer Reports is still testing the iPhone 4S and is working on a new report on its battery life. It's also looking into Apple's new iCloud, which allows users to share music, photos, apps and more on different devices.
We'll report on those tests as they come in.
View images of Apple's new iPhone 4S, unveiled last week at the company's headquarters.