Constructive criticism from a fellow designer

This app still has some bugs and needs to be tested a bit more before full release.

-once you max out, the button for the last number sometimes stays selected.
-when selecting the effect, it is annoying when it plays the effect randomly itself while I am pressing the screen.
-Even though there is space between the buttons, it should still be part of the hitarea of the buttons. So if there is a 10px space between [1] and [2], if you press 4px to the right to 1, it should count as a press, especially on a touchscreen.
-the app sometimes feels unresponsive with the visual feedback of pressing the buttons.
-the zipper is unnecessary for history. For the simplistic theme of the app, you could have the history show when you swipe down from the display. It would get rid of the ugly icon in the middle of the screen and you could made the keys bigger. The settings icon could then be found along with copy and paste when you tap or in the history menu.
-in the history menu, you should hide the display. Your last result is shown in the history anyway, so it has no use and is taking up space for viewing history.
-the black design looks really sleek and sexy on a black iphone, but you should include a white version for white iPhones. (Mines black btw)
-when you swipe the keyboard to the side, you could have more functions

I hope you take this advice into consideration.

Codderr about Llumino