I think it's cute. Sometimes after being outside all day, you know how you can get a chill at night? Looks like a great beach coverup, too. Or for boating - nice colors for the boat deck.
I actually do wear long sleeves in summer; it can get over 100 here and it's plenty humid, but I like to shield my arms from the sun. I find covering up can be cooler than too much exposure. I generally wear a hat, too.
I thought Carolyn looked good in it, and it pairs well with white bottoms. I don't need it, but I'd get the bright navy if I were to buy one (though most sizes are sold out in it).
Cogito ergo sum