Some of the things that stood out to me in Unreal Engine 4 interface and navigation were:
1. The ability to drag and object and have the camera move with you. Personally, i think this is a huge time saver and makes it much easier to navigate whilst orientating objects.
2. Being able to pop out the viewport and have it on a seperate monitor. This makes life easier with two monitors, similar to having Rhino on one screen and Grasshopper on the other.
3. Having up to 4 content browsers and being able to lock them, making it much easier and quicker to access different materials and objects without having to go back and fourth.
4. The 'Lock viewport to actor" to control lighting with the normal viewport controls is game changing. Positioning lighting in rendering software is critical and being able to control the lighting like this makes it so much easier and faster to do.
5. Lastly, the simple yet extremely useful command to snap objects to the floor. A simple yet effective command to make life easy.
Unreal Engine 4s level design also had features which stood out, such as:
1. The ease of creating, copying and subtracting geometries, similar to the pull/push command in Sketchup but far quicker and easier to use.
2. The application and ability to orientate textures and materials. Mainly this i found to be an issue in Sketchup when applying the same texture to multiple surfaces and they didn't lineup yet UE4 makes it easy with a click of a button.
3. Blueprinting animations, similar scripting to that of Grasshopper where objects are referenced but animating the objects to move according to the prop was far less complex than expected.
4. Physics for objects being as simple as checking a box really stood out for me, UE4 making it that simple to create physics for objects is a great assistance.
5. The lighting and dynamics of it through the use of reflectors are interesting, the ability to control it just like a prop is far easier than that of trying to place lighting in rendering objects, especially when you can enter 'game mode' in UE4 and test the lighting.