The only issue I have while playing Graal on my iOS device is when I've been playing for a while and then I wash my hands (for whatever reason). When I come back, the screen just doesn't feel right. It gets kind of slippery and I'm unable to use the controls with the same level of finesse I'm used to.
Never played Graal on PC. I'd imagine it would feel weird given that I'm so used to playing it on my iOS device.