Here it is, the tl;dr of the new Apple iOS 11 security updates.
Apple iOS 11 is available for iPhone 5s or later, iPad Air or later and iPod Touch 6th gen.
If I can count, there’s 15 CVEs that were addressed with the September 19, 2017 Apple iOS 11 release.
These have to do with features like
WebKit, and Wi-Fi.
Denial of Service,
Should you download it? I say so. There’s enough security built-in that you should. Make sure to back-up before you do. I can’t help if it fails 😛
For more information on the update, check out the Apple page: https://support.apple.com/en-us/HT208112