There is a screen that tells you, but only if you have apps that won't work under iOS 11 [and this is coming from someone still using iOS 10, so this may be different].
Go to Settings->General->About.
If there is a > after the "Applications" area, then tap it. A new screen appears with a list of all apps you have that won't work in iOS 11. If there is no ">" after the Applications section and it just lists the total number of apps you have, then that means all of them will work under iOS 11.
You will need to count the number of apps in the list, but at least there is a central spot for seeing which ones are incompatible.
HTH.
[doublepost=1511047107][/doublepost]
I'm still on iOS 10 and have the original Words with Friends. It does not show up as needing updating in the list of apps that I have installed. [eg: AppShopper, iMAME, iDOS, Hueless, being my favorite ones that aren't going to work in iOS 11, though Hueless devs stated they will release a 64-bit version soon]. Does WwF not work under iOS 11 for other reasons?