The display size of the Galaxy Note 4 remains the same as its predecessor, at 5.7 inches, but it has a higher (2,560 by 1,440) pixel resolution. Both the Galaxy Note 3 and iPhone 6 Plus's 5.5-inch touchscreen have a resolution of 1,920 by 1,080 pixels. I didn't notice much of a difference when reading text, but when looking closely at images and video, I found that the Galaxy Note 4 showed sharper details and produced warmer colors. It's truly a beautiful screen, and outdoor visibility was also good.
The Galaxy Note 4 runs the latest version of Google's Android operating system (KitKat 4.4.4), along with Samsung's TouchWiz overlay. While general navigation is easy enough, the Galaxy Note 4 is bogged down with extra software and services from Samsung and, in my review unit, AT&T. I didn't find a majority of them to be useful, and I have other apps that I prefer to carry out the same functions, so it was frustrating to have them cluttering my screen with no way to uninstall them.
As with previous models, the Galaxy Note 4 includes an S Pen stylus. Samsung said it increased the sensitivity of the stylus to make it feel more like writing on paper. I wouldn't go that far, but I found that taking handwritten notes on the phone was smoother and more fluid than what I experienced on the Galaxy Note 3.
Read MoreQualcomm trumps Microchip with $2.5B deal for CSR
On the back, you'll find a 16-megapixel camera (up from 13 megapixels) with optical image stabilization, which helps reduce blur caused by shaky hands, and improves low-light performance. Picture quality was impressive, even when I shooting photos in a dimly lit concert hall. The front-facing 3.7-megapixel camera also has a wider lens, so I was able to capture more background scenery when shooting selfies, compared to the iPhone 6 Plus's front-facing camera.
General performance by the Galaxy Note 4 was smooth and swift, thanks to a 2.7GHz quad-core processor from Qualcomm. I didn't experience any hiccups while working in multiple apps, streaming videos or playing games. I also made several calls in the San Francisco Bay Area using AT&T service, and call quality was clear.
While I didn't run a formal battery test, I easily got more than 24 hours with moderate to heavy usage. It's also worth mentioning that the smartphone uses Adaptive Fast Charging technology that helps speed up the charging process. Samsung says the Galaxy Note 4 can go from zero to 50 percent battery life with just 30 minutes of charging, which was accurate in my testing.
The Galaxy Note 4 builds on an already strong product with improvements to key features like design and display. But with competitors knocking on the door, Samsung will need to make some bolder moves.