Instead of one huge cluttered window full of tabs, you see this window first and then when you click edit you will see an appropriate window for editing the item. This way I can also add shortcuts in case, for example, you're selecting an enemy for something and decide you want to change it from where you were.
Inheritance is a very good feature, it lets you create items much faster and makes it easier to edit tons of items quickly. For example, you can make a basic Potion item as a parent and then have children where only the icon, value, and strength were set. You can then edit the Potion parent for the other fields and they will be set for all children of Potion. It's like Map Properties but for everything.