Thanks for the Mac OSX version! I have been messing around with it for a bit, definitely takes some time to adjust to the controls. Here are some thoughts.
1) When zooming out on the OSX version the polys and even primary vertex disappear and there is just a black screen until you zoom in more. Appears to be a glitch.
2) Detachable Tile screen and having a zoom will be key.
3) Making buttons for more of the controls will be good, just too many keys right now.
4) Orthographic project. This needs to be an option for how you view stuff.
More thoughts about how I would use this personally. I think this tool would be amazing for making isometric maps in the style of Final Fantasy Tactics.
I think having the option to lock a base layer to build off of, and to have basic isometric views to easily rotate around with would make thinks much easier. There are also common isometric shapes that are a bit cumbersome to make with your current options (like a single unit pyramid). I get the idea of painting with tiles, instead of painting starting with shapes, but having a few basic shapes that you can quickly apply tiles onto might make things more efficient. I'm hoping to reproduce a FFT map in the next few days to test things out.