I did not change the icon sizes. The icons I downloaded are 128x128 in size. The default ones are 55x55. So the neo interface reduced my 128x128 icons to something between 128x128 and 55x55. You only have to change the size of icons that you want to change. It'll be perfectly fine to leave the inactive_state icons at a small size and only enlarge the active_state icons for an extra pop effect. The home icon (second talk bubble icon) has four states, unlike the other icons that only use two.

I didn't even bother to resize the icons and the neo interface will shrink them to fit. It's kind of neat having the icons being so big and a little overflowing and bleeding off the screen.