Security updates this dense are easy to skip, but this one has a few features worth enabling the moment it hits your phone. While I always try to live on the bleeding edge of updates (I update operating systems, apps, and other services almost immediately), I know plenty of others who either hold off on updates or just ignore them. I often have to nag even my own HighTech family to do the updates.
But, any update that includes security fixes is pretty critical to do fairly quickly. This update seems to have the underpinnings for an “anti-theft” feature, which is always good to have. Also, several vulnerabilities have supposedly been patched.
There are also updates to macOS and iPadOS that include the same or similar security fixes so I would highly recommend updating your devices when you can. Always be sure you have a backup!