I did this route in winter conditions, and the views to be had around the Derryveagh Mountains, over Dunlewey, and across the Poison Glen are excellent. I was only doing Drumnalifferney NE Top, having missed it out on a previous walk, but the route could be easily extended to take in other summits. I was also stopping for a lot of photos, so the route could definitely be done quicker.
The view across the Poison Glen. Looking down over Dunlewey. Low evening light catching the mountain tops. The last of the sun on the face of Errigal. Lingering until after sunset.