Very convenient on iPad Pro 12.9" iOS 16
Given dates of earlier reviews, I worried that Handy keyboard wouldn't work on current versions of iOS. It works in iOS 16, and is absolutely worth the price for me. Without a split keyboard, an iPad Pro 12.9" would be nearly useless for my purposes. For me Handy is much better than the only other good alternative, Banana Split. The advantages of Handy are that (a) you can shift the keyboard up, allowing you to hold up the iPad with your other fingers, and (b) the keys are small and close to the edge of the screen. Larger keys could be easier to type on, in theory, but the result is that the inner keys are far from the edge of the screen, causing errors because my thumbs have to stretch too far to reach the inner keys. I don't have problems with Handy's small keys. My one complaint is that the little globe button for switching keyboards is in the center where you can't reach it easily while typing. (I often have to switch keyboards momentarily to type a Greek letter.) It would be nice if the space where there are no keys were transparent, but this seems to be a problem with the options that Apple allows developers, and I don't mind, most of the time, if the part of the screen below where I am typing is covered up. (UPDATE: I tried to use the Handy Keyboard on a recent iPad mini, and it didn't work, but the HK would more or less duplicate functionality that the built-in Apple keyboards already provide on the Mini. Where I need what the HK provides is on my 6th gen iPad Pro 12.9", and it's great there. I haven't tried HK on any other iPads other than the Mini.)