There is one more thing bothering me: The touch areas are not visually distinguishable. I was really surprised that touching just a little left of the minutes will scroll the hours, even though there is no line between them and there is a huge whitespace inbetween.
I'm thinking that whole roll picker doesn't fit into flat design at all, since it's depicting a 3D object, which is the very opposite of what flat design is about - whether you like it or not. I do think that flat design done right can look great whilr offering the same usability, but it's much harder to get right.
I'm not an iOS user - has the date roll picker always been there? In WP7 (the exemplar of flat design on a phone) it uses the roll-like UI but without the 3D object metaphor. The behavior is the same, but flat.
I'd rather just have a numpad, especially for time.
I'm thinking that whole roll picker doesn't fit into flat design at all, since it's depicting a 3D object, which is the very opposite of what flat design is about - whether you like it or not. I do think that flat design done right can look great whilr offering the same usability, but it's much harder to get right.