Summary
Just tested the new v4-alpha2 Duality project template and installed the Tilemaps sample package into the GameEditor project. Everything worked as expected, but there is one issue that might easily throw off new users and could also annoy experienced users:

All the installed content files actually show up in the project in Visual Studio, and they can be edited via double-click. That alone would be tolerable, but any changes made are simply ignored and don't end up in the actual project.
There are a lot of internal theories on how Duality works that new users might develop based on that, most of which would lead them into the wrong direction, so I'm flagging this as a usability bug. If possible, we should fix that in some way before the actual release.
Analysis
Here's a number of ways this could be fixed, though I don't really know how difficult any of them would be - @Barsonax probably has a better idea on that topic.
- Hide the content files completely, so they don't show up in the VS project.
- Keep the content files read-only.
- Make sure any changes made to the content files end up in their copy in the actual project.
The last one is probably a bad idea, since that would mean letting users edit the content files in their local package cache directory. I'd probably go with the first option to avoid any potential confusion in the first place, if there is a way to achieve that.