"To Autumn" goes way beyond just mere appreciation. Keats' poem does appreciate and glorify the season, but a deeper reading of the poem suggests a theme of peace through acceptance. The autumn season signals the end to the glorious summer; Keats' poem celebrates the end of a beautiful time.
Through "To Autumn," the reader can learn the value in letting things go, the art of acceptance. Keats' poem models how to achieve this peaceful acceptance, like in the way the speaker of the poem can look back on the the beauty of spring and summer flowers--but he does not dwell on their loss--rather he looks forward to the promise of the coming year. He focuses on the here and now, relishing the time he still has. Keats' poem does pay homage to the beauty of Autumn but also cleverly illustrates how to cope with loss.