I belive the IOS version of Photoshop should include a brush that does not automatically appy anti-aliasing. The pencil tool on desktop is a good example, or simply the ability to turn off the spray of semi-transparent pixels that hoarde around the edges of my every brushstroke. Be it through a checkbox or a true "100% Hardness".
All my work has been with aliased lines, meaning that I downloaded the app only to find out it was funtionally useless to me. I knew not all features would be accesable on mobile, but the pencil? I implore you to consider adding this age-old feature to mobile so I can enjoy creating in Photoshop on the go!!