What are the advantage and disadvantages of Project From View unwrap method? I would like to know how is the disadvantage to unwrap with the option Project from view

I think is very useful for sharp angles such 90 degrees or planar geometries , but I think is not useful for shapes such as "ornaments" for example , Medieval houses , where there are ornaments with rough or rounded shapes.

I think I can not export that kind of UV mapping, I like or prefer Mark the Seams and I think I have more control on the UV.

Should I avoid this method for export the UV's to an engine such as Unreal or Unity? 

PS : I think project from view is useful for Ccycles or stuff to work only in Blender, not for export, not for very professional, but it is useful just quickly method to avoid seams.
You might have a photo of an object in real life that you want to map onto a 3-D object.

So you align the 3-D object to be in the same angle/scale as in the photo and project from view it so that the photo gets a bit more depth than simply flat image being manipulated.

If you have a persons head photoed from different angles, you can stitch together the face using this method.

https://www.youtube.com/watch?v=sZDMFkj8GqA