I bought my first iPad in 2010 and have upgrade to each new iteration including the 10" iPad Pro. But after iOS 11, I sometimes feel helpless using my iPad. I think Apple needs to ship iOS with a manual. Some of my colleagues may disagree but I think the changes in iOS 11 are significant and in many ways are such a break with the previous versions of iOS, that Apple may have to consider shipping a manual with iOS devices, and may have to start doing more in-store training1 for new users.
I just tried to use Split View with one of my banking apps. Normally I would open 1Password and copy the complex password and paste into the app password field. However, this banking app won’t allow pasting of passwords and also has a “special security question” for authentication. The problem with special security questions like "Father's middle name" or "College you attended" type of questions is they are neither special nor secure. If you have a LinkedIn profile or have ever applied for a job that information or suffered a data breach2, most or all of that information is findable. For that reasons, I use made-up answers for the "special security questions". I keep track of them in 1Password. I needed 1Password open to see the app password and special security question to type into the banking app.
On iOS 9 and iOS 10 split view was enabled tapping the middle-right of the screen of the open app and swiping left to see the app-picker before selecting the second app. It wasn’t elegant — if your use a lot of apps the scrolling list was annoying — but it worked.
That no longer works on iOS 11 and there may be at least three different ways to do it. I just spent 15 minutes reading various articles — none of which were written by Apple — on how this works. The method for the iPhone differs from the method used on the iPad Pro and from the IPhone X. I was successful in using only one of the three methods for starting a split screen session. Dragging one app icon while tapping another is a gesture I have yet to use successfully.
I think we’ve hit peak complexity. Apple added multitasking and split screen because they are marketing the iPad Pro as a productivity tool. I think a manual is required to learn about all the new features and gestures. It doesn't need to be a physical manual; an app, installed on the home screen, would suffice.