I bought one last year, and while it's still small, it is showing fall color. It gets a fair amount of sun, but not full sun like I think it's supposed to. So far, I'm happy with it. Give it another year and more sun if needed.

I am in the northwest suburbs of Chicago, and while I don't have amsonia, a lot of our fall color trees and shrubs were lackluster this year. Our sugar maples have had hardly any color, the burning bush have been spotty - I've heard it's due to our long streak of warm weather. Some plants have colored great, others not. I'd give it more time.

Thank you for your messages!
I agree that this year's fall color is somewhat disappointing. I was thinking that maybe I should call the plant clinic in the Morton Arboretum as I've heard that they are very responsive. I will try transplanting to a sunnier site next spring in the hope of getting outstanding fall color.