2 issues I ran into:
- Views revert back to default sizes when you restart the application. (View sizes aren't saved)
- Can't select textures from texture browser and MMB them. You need to apply them with ctrl + click first, then you can copy them with ctrl+MMB and then MMB everything else.
The hotkeys take some getting used to if you're switching from gtk radiant, but they do seem to be easier once you get the hang of it. Except that E is now merge instead of edges :D
The new room button is great and I'd suggest to just get rid of the make hollow button.