Skip.
Four-Mile Vista is a viewpoint near Colton Point State Park. To get to it, you have to take a small, unpaved road for a short distance (the road is packed gravel, so it isn't terrible). The road is about 1.8 cars wide, so getting around an oncoming car might be nerve-wracking in some places. The pull-off for the vista is just a mud parking area beside the road.
The vista itself is underwhelming. It is called Four-Mile Vista because it looks down the valley cut by Fourmile Run, not because you can see four miles. The view is very framed, it isn't a wide open view, you look in a very specific direction and that is it, there is nothing else to do. It might be more impressive in late fall/winter/early spring when the trees don't have as many leaves, but when I was there it was not worth stopping at.
So to sum up, I would recommend skipping this stop entirely.
Pictures of the view can be found at: