Good starting point on trip round Tokyo
On clear days - especially in the cold season - you will get a spectacular view over Tokyo to the mountains and see Fuji very clearly. A good place to take overall photos of Tokyo and free. The view from the Mori Tower in Roppongi is better if you want to see neon all around but it is pricey. The views are great but the observation area, office-like. Still, look out of the windows and you won't be disappointed. Very convenient from any of the hotels in the Shinjuku area.