I'm always interested in improving the design, and fairly recently updated all icons to the new material style, and continue to tweak it as time goes on.
That being said, yes, there are places where some of the -- what I feel -- "smaller" things are not completely up to spec.
- The navigation drawer is supposed to slide out *on top of* the phone's status bar
- Margins / paddings / font sizes may not always be "spot on"
- In general, I feel it's more common (and maybe "more material") to use more padding everywhere than AquaMail does, that coveted "clean" look, but then I'm not sure if reducing the amount of visible information is always a good tradeoff.
Please note that there are -- very pretty -- apps out there that seem be more "iPhone style" than "material design" style really.