I agree it depends what you're used to. Where I live is mostly pretty flat in most directions - there are a few steep hills but nothing hugely long (e.g. one hill is 10% but only for about 400 yards).
When I visit friends in PA who live in a valley I see the descents with warning signs "8% for 3 miles" etc, and see some of the other ridges, and figure that's nothing like I will ever experience around my normal cycling ground.