I think that this is the best 4 of Cups I've seen. In other decks I'd probably have to have some help from the LWB or another text to know what's going on but here it's so clear, the young man oozes ennui and boredom.
The mosaic gives a kind of Impressionist look - a broken-up shimmering of light and colour. To me this represents the magic and beauty that surrounds him, but that he's incapable of seeing. Perhaps he only sees the little, individual bits and they look small and paltry to him - he doesn't see how it all fits together into a glorious whole. It looks like springtime, but maybe he wants summer. It's a beautiful rural landscape, but perhaps he's dreaming of a big city where the streets are paved with gold. Maybe he's lonely, sick of the solitude of being a shepherd. I guess there's a lot of him in most of us. I feel sorry for him, but at the same time I want to shake him.
The goblets that form the pattern of the four cups in the foreground are a very satisfying shape - solid and fat and rounded, for all our languishing hero knows they could be full to overflowing with nectar. To me they're a reminder of craftmanship, of getting involved in work, of dynamically shaping something from nothing. A big hint to our friend the shepherd about a way he could choose to go. But can he snap out of his reverie, to see this?