At this time I do not recommend upgrading to iOS 11 especially if you have an iPhone 5S.
Based upon my own experiences with iOS 11, Apple needs to iron out some more wrinkles with the software to refine some features and to improve overall performance on the iPhone 5s. iOS 11 slows down the iPhone 5s and increases the waiting time or “hanging” time from when you open an app (like Notes for example) until you can actually use the application.
Therefore when you receive the “new software update” notification for your iPhone, iPad, or iTouch/iPod Touch tap “not now” or “remind me later” to delay installing the update. Later I will post a guide on how to remove the update only if you’re in the time period AFTER you accidentally tapped “install” but BEFORE the update was fully applied.
If you actually applied the update and don’t like iOS 11, it may be possible to downgrade but not without challenge and/or time cost. Contact me and I’ll either give you a free estimate for me to do it for you (if you’re in the greater NYC area) or I’ll quickly just tell you over the phone.
Although a warning, in order to downgrade EVERYTHING will be removed off your phone and that EVERYTHING includes messages, saved app data, open web browser windows and more. It will be like resetting your iPhone to the first day you bought it with NOTHING on it, zip, zero, nada. Finally time is limited on when you can do that; usually within a week or less of a new update Apple removes the ability to revert to the old iOS version. Therefore time is of the essence if you accidentally updated/upgrades and want to go back.