I started to use DP3 recently after being a long time DP2 user and had a few random comments / feature suggestions for you @Warlander
Make it possible to hide the shadows in 2D view - I've found compared to DP2 it makes it super difficult to work in this view because it's hard to see the tiles clearly
Speed up the 2D WASD camera movement a bit more as you zoom out - it seems to keep a constant speed no matter the zoom level but I think it would feel nicer if it scaled with the zoom level too else it takes ages to pan across a large map without using MMB dragging.
I love the new height editing in 3D view, but it would be great if there was a way to select by tile and not only the corner handles, as it's quite awkward sometimes to try and get all the corners you need and I find you need to keep shifting around the camera to try and avoid grabbing handles of other tiles that you don't want. If I could e.g. set the target height in the level area function and just click through each tile, or use the select + drag and be able to drag by tile face selection, that would save a lot of time. Basically like an option between vertex and face selection.
Not sure if there is one already, but a shortcut for moving up and down layers would be really useful too, something like ctrl + mousewheel up/down and secondary of pageup/down?
A way to speed up frequent saving would be a major time saver, though I realise this isn't quite how DP is treating the map files at the moment, but usually you'd open a document, and then that's the active one and you could just ctrl-s and it'll save over it, whereas here you need to constantly go to menu->save map-> save to file -> pick the same file that's already open-> yes I want to overwrite.
Being able to place objects in specific places now is great but I noticed right click removal is still wiping the whole tile of objects, would it be possible to change that to per-object removal as well?
Add a small delay to detecting the right button mouse button being held down to delete multiple walls, because this triggers now even if you only perform a click, so if you are looking at a wall and there's other walls behind it in the distance, if you right click to delete the near wall, it's like shooting a laser through the whole map and nuking every wall along the path.