Most people must be using the path Blender => .blend => Unity.
My preference is Blender => .fbx => Unity, which has additional issues. It's strongly advisable to:
If not, you can/must clean up a confusing mess in Unity ;) :/ . I spent a lot of time learning this the hard way.
[I did watch the export/import in the Unity stream. I don't remember if it was mentioned there or not.]
If you change the units, be sure to check/adjust the camera clipping. Going to centimeters seems to set clipping "1mm/1m" which causes weird unexpected behavior. I set it to something more reasonable like 1mm/10m or so. (In fact I have an empty .blend file with all my preferred settings, which I copy to start each new project.)