This is an old story "do not use built-in flash!". I think every photographer heard this many times.
But why? Yes, it creates harsh shadows in many conditions, especially if background is close to object.
But after my try to use this during events where distance was more than 3 meters, i discovered that built-in flash gives better results than external one.
My equipment: Nikon D800. Lens - AF-S NIKKOR 24-70mm f/2.8G ED.
Event: evening parade during Carnival 2015 in Halle, Belgium. Editorial work. Distances from 5 to 30 meters.
I posted links to whole images to give an impression of the distance and 100% crops to see the quality which was in output.
I am very happy with results and less weight of my photo bag!
Using small tricks which don't weight more than 100g i do beautiful shots from closer distance with built-in flash too.
Nikon did great work.
Original images (left side) and 100% crops (right side):