On paper, Samsung Galaxy Note9's cameras look pretty similar to Samsung Galaxy S9+'s cameras. Reality is, even though they've certainly taken inspiration from Samsung Galaxy S9+, there's a lot of AI magic involved to make Samsung Galaxy Note9's camera even better.
Phone is equipped with two 12 MP sensors having one telephoto lens and other a wide-angle lens. Telephoto camera has Dual Aperture feature from Samsung Galaxy S9+, which opens up to f/1.5 from f/2.4 to let in more light while wide-angle lens has an f/2.4 aperture. This allows for more light to enter lens, meaning even dark shots look good. Even when using Live Focus (aka portrait mode), which is usually problematic in low light, camera produced a great looking photo, especially when compared to Apple iPhone 8 Plus's lackluster results in same lighting conditions. Second lens adds same 2x optical zoom you get on previous Note, and you'll naturally be able to take bokeh-style photographs with Samsung's Live Focus mode.
Samsung has also added something it calls Scene Optimizer, which is basically its version of Huawei's and LG's AI photography feature. It is intelligence baked in for automatically configuring camera settings depending on what you're shooting. Phone's camera recognizes 20 different scenes, including snow, sunsets, beaches and backlit subjects, and adjusts contrast, brightness, saturation, white balance and other settings you'd normally have to manually configure in camera's Pro mode. In my experience this feature worked decently well, bringing out a bit of extra color in things like flowers and other greenery. Obviously, it's not going to be perfect. I found, in case of flowers that it has a tendency to oversaturate colors. If you agree, you can turn off Scene Optimizer if you'd rather take photos without its intervention as well. However, you have to do this before shot is taken. There's no way to manually override this feature to tell it what kind of object you're shooting.
There's a brand new featured added by Samsung in their new Note smartphone's camera which is called Flaw Detection. It serves a similar role as Scene Optimizer, helping you avoid getting in your own way as an amateur photo. Feature is designed to alert you if a shot is blurry, if there's a smudge on screen, if subject blinked or if backlighting is making everything look crappy. In case of lens smudging and backlighting, it only bothers with an alert, every 24 hours. I found this feature somewhat useful as blink detection worked well. Blur detection, on other hand, was a bit more of a crap shoot for subjects in motion and those that were too close to the lens to get a good focus. This feature could use a bit of work, but I still think it's one of the more compelling additions as a whole of device as I anticipate a lot of other companies introducing their own versions in coming year.
You can record videos up to 4K at 60 fps, 1080p at 240 fps and 720p at a super slow 960 fps. Videos are shot with HDR on, which delivers exceptional footage even in low light conditions. Both camera lenses also support OIS (Optical Image Stabilization) which help to deliver exceptionally stable videos even while you're walking or even running. On front, there's an 8 MP selfie camera with an f/1.7 aperture and autofocus that allows brighter selfies in dark scenes while you can also shoot 4K videos at 30 fps from front camera, quite impressive indeed.
Overall, Samsung Galaxy Note9's camera is solid, but it's not the best around, even with Scene Optimizer activated. Its biggest competitor at this moment is Google Pixel XL which delivers the best smartphone photography, closely matched by Huawei P20 Pro. However, being able to ditch AI and shoot in Pro mode when you want to and features such as AI scene detection with dual aperture is a nice touch for professional photographers and smartphone camera enthusiast.