There are a lot of reviews of iOS 11 out there already and as is almost always the case, people are complaining that things changed. This is not that. Part of the reality we live in with our consumer-oriented technology demands is that things change. As a whole iOS 11 seems to be an improvement over previous versions and in general I'm happy with it.
Apple continues to take security seriously, now requiring passcode authentication after repeated failures as well as after reboot. Also requiring the phone to be unlocked to exfiltrate data is an improvement. This focus is especially important with the continued focus on privacy and security in the face of difficult times all across the world. This kind of behavior should be the default on all mobile devices.
Third Party Location Use Alert
In previous versions it seemed that Apple Maps was the only navigation program that would present you with the blue bar across the top of the screen, letting you know it was actively using your location (and providing a low-friction way to task switch back to navigation). Obviously you shouldn't be using your phone while driving 😔 and the DND While Driving mode is a nice feature (though I doubt anyone is really using it) but since the Podcast app is now broken (see below for more), if you find yourself changing music or some other totally reasonable action while driving it is nice to just be able to tap on the header to go back to your navigation app.
Phone Controls While Locked
This is seriously great. Not having to unlock the phone to toggle mute, or to switch audio outputs, or to end the call is a great thing. Even if you don't fanatically toggle mute while on conference calls, at the very least this has totally gotten rid of the 3 seconds of awkward silence after you say "goodbye" while both parties root around trying to get to the 'end call' button.
Stupid Home Control Bug (still)
I think this has been around as long as the Home Control feature has been in iOS. I remember it on my iPad Mini 2. It seems that when you turn this off, it always ends up turning itself back on. Thankfully I don't have any HomeKit devices because frankly this is a security bug. I don't want someone to be able to see or interact with my home automation without being authenticated. That's just... shocking. It's like having a lock on your door that doesn't need a key. What is the point?
Podcast App Now Basically Useless
I listen to podcasts while driving, mowing the lawn, working around the house, and sometimes while working at work. I am DEEP in the back catalog of most of the podcasts I listen to so I don't want to have to stop what I'm doing and pull the phone out to navigate to and select the next episode. In previous versions I have not had to. For some reason now the built-in Podcast app stops after every episode, even if there are more unplayed episodes already downloaded to the device. This seems strange for Apple as it increases friction using the device.
App Search Completely Useless
I don't like having a pile of apps on my home screen. This is similar to how I use my MacBook Pro. I toss everything in a folder and search for what I want when I need it. On the Mac clover+space works great. On the previous version of iOS this same workflow worked well. Swipe down, type two or three letters and the app you want is probably listed. Tap and launch.
As full disclosure I have always had Siri and all the related Siri features off since I have had it on all my iOS devices, but in the past this worked great.
Now however you have to type the entire and exact name of the application for it to show up. This makes the workflow much more difficult and cumbersome. More friction for no reason.
iPhone Force Touch App Switching Gone
With all the focus on the iPad, multitasking on the iPhone lost a really handy feature. In iOS 10 you used to be able to force touch on the edge of the screen and get the task switcher. This was less movement and already had your thumb on the screen to switch or close apps versus the double-click home gesture. Again, more friction for no reason.
New Apple Visual Style
I feel like this is the most subjective of the changes. While the UI has changed a LOT over the years and is largely an improvement I can't help but by a little bothered by the waste of space that comes along with the new design language. The fairly ubiquitous search bar just off the top of the screen is nice but the giant title of the app you just clicked on seems... a bit superfluous. Maybe this is less of an issue on the larger screen devices like the iPhone X and the iPads, on a regular iPhone 7 you have a solid 1/4" of the display taken up by quite literally the name of the thing you just tapped on.
Native Video Controls Now TINY
I don't have a lot to say about this, but the native video player controls are now much smaller and harder to hit. The volume overlay is better but the rest have gotten markedly worse. Most of these aren't a huge issue but trying to hit the full screen or AirPlay buttons has become much more painful. Like I said about the visual style this may be less of an issue on the larger devices, but on the smaller screen standard devices it is pretty irritating.
Overriding Settings To Default On Upgrade
One of the more ugly things that iOS 11 did upon upgrade was to turn on a whole bunch of features that I explicitly turned off in iOS 10. Things like iCloud, iMessage, and Siri turned themselves on without warning. I declined the iCloud Drive feature during setup but a bunch of the other features popped on and iCloud added itself as an 'Account' automatically. I can imagine this was part of some preferences migration in the phone since things clearly have changed but it seems like the case where the user had previously disabled all this had not been tested or possibly (worse) someone had decided to ignore the user's wishes and turn this stuff on again. It seems like I caught it before it started syncing anything back to the Apple mothership, but it feels like a potential privacy leak. At the very least it required an audit of all of the options in Preferences to verify things weren't being uploaded to Apple which was a waste of time and added friction to using the device.
I Miss Steve Jobs
You can say a lot about Steve Jobs. He certainly had a very storied career. For all the drawbacks of his fanatical and perhaps ego-driven attention to detail one thing that was true under his stewardship of Apple was his focus on polish and reducing user friction with technology. This version of iOS, while being largely good is somehow lacking the polish that I would otherwise have come to expect. I don't know if it is the reality that he's gone and his curated plans for the products he shepherded into life have finally ended or if it is the inexorable pressure of the market on Apple to continue to 'innovate' on a very aggressive 12 month cycle. Either way it is a stumble, and while all technology is created by humans who are by their very nature fallible and under enormous pressure to remain the most valuable company in the world, I do hope that these things get polished away instead of becoming a canary in the coal mine for the future of the product.
You Should Still Upgrade
All of the nits I picked above aside you should still upgrade. The security and stability updates alone are important enough to warrant keeping current.
Steve Jobs headshot used under license, see here for details, iOS 5 screenshot from Softpedia