The island is long and narrow, east-west. Reykjavik is to the south and Mount Esja to the north. The island itself is relatively flat and covered in grasses and flowers. No birch trees - and also no lupins!
On the western half are a few pieces of art, including some monoliths by Richard Serra, and an incredibly uninteresting piece by Yoko Ono. The eastern half has ruins of the fish-drying operations and village that were once there.
But the birds - I saw and heard plenty of them, most of which I can't identify. However, I did see and hear and can identify the kría, which I'm pretty certain was one of Hitchcock's inspirations. This bird divebombs your head if it thinks you're in their territory. And the trail designers of Viðey decided to put part of the trail right next to prime egg-laying area. Seriously, people? I had some truly Tippi Hedren moments.
Aviary aggression aside, what is most notable about the island is how peaceful it is. Even when you can see the city, it feels very far away. We were fortunate to have a beautifully sunny day, with views of the mountains and the bay beyond the rustling prairie. The wind and the birds dominated the soundscape; the occasional aircraft broke in, but not startlingly so - unlike the ludicrously loud hedge trimmer being used upon our arrival.
There is enough hiking to occupy you for the afternoon, but you could also find a nice vantage point and watch the waves and the grass for a while. Bring a picnic and a sketchbook if that's your talent.