I wouldn't know, they're definitely popular here. GDIs have started to wear them en masse along with Oakleys (ugly). I prefer Ray Bans myself but I have seen some really nice costas (LOVE their blue frames).
Yes, GDIs are running all over the place with them. But every Greek has them here. I like the ones with the green frames. Oakleys are starting to die out around here, its pretty much 100% costas.