The iCloud Photo Library was designed to let you easily sync your photos between all of your devices. If you have it enabled on your iPhone, then you can turn it on on your Mac or iPad and instantly access all the pictures you've taken with your iPhone. Additionally, any photo edits you perform on your Mac will immediately be reflected in those photos on your other devices.
The ability to take a screenshot has been around for a while and is useful for a variety of reasons, whether you are using them to write a tutorial about a game or just showing friends the contents of a message thread. Whatever your reason, annotating a screenshots can make them a lot more useful, and iOS 11 has overhauled the screenshot process to make it that much easier.
Apple continues to add tutorials to its video collection directed at iPhone photographers. From the basics to useful pro tips, there are now over 20 step-by-step instructional videos in How to shoot on iPhone 7. The latest additions showcase the Memories feature of the iOS Photos app. Memories was added with iOS 10, along with other highlights such as the People folder in Albums.
Photos taken with the iPhone, or any digital camera for that matter, contain a variety of metadata including EXIF data (camera related data such as aperture, exposure, lens, etc.), GPS data and timestamps. This data can be accessed by anyone you share the photo with, so it clearly raises privacy concerns, e.g. you post a photo of your house that includes GPS coordinates of where your house is. Unfortunately there are currently no tools native to iOS that can remove or edit this metadata, so third party apps are required.
Anybody who has started a video recording with their iPhone or iPad and promptly decided to switch from portrait orientation to landscape (or vice-versa), has found upon replay that the orientation didn't change, resulting in the majority of the video being sideways. Even though everything looks fine during the recording process, it doesn't translate to the finished product - an issue that Apple perhaps will address at some point.