I tried it for a while but gave up. It may be possible to get up to the typing speed of a regular keyboard, but it’s main purpose is to be less error prone than a more traditional touchscreen keyboard. Gboard and others use autocorrect to make up for how easy it is to misclick, but that requires large libraries and (in Gboard’s case) telemetry/data collection. Thumb-key’s advantage is it’s simplicity. It doesnt need autocorrect or predictive typing, because the buttons are large and the gestures are well defined and distinct. You should very rarely accidentally type the wrong character once you’re used to it. I never got over that hump, but I’m sure some others have and enjoy typing without looking like we used to be able to do on physical keypads.