I suppose it's useful when almost everything works, but that one thing that you absolutely need isn't otherwise available.
Like: the VSE viewer and the Image viewer are similar but distinct; that can be confusing. And OpenGL acceleration on a Scene strip shows a 3D model rendition that is not (in general) the same as the rendered output of the Scene.
If you want to get fancy with the compositor + VSE, again there are just a couple of quirks but the learning curve is merely steep, not long.
The open source alternatives are no where near as fast, they lag far behind supporting new cameras, their interfaces are ugly and difficult to use, etc.