Catherine looks wonderful and elegant. The colour of the dress suits her, and I love the lace. I also love Catherine's hairstyle too, and it's nice to see her experiment with her hair a bit more. She looks fabulous in buns! The only parts of her outfit I don't particularly like here are her shoes and earrings.
The Daily Mail are claiming that Catherine has influenced Mary and Letizia with lace - wake me up when they start writing articles about 'real' news. Royals have been wearing lace before Catherine married William, so it's not as if she started that trend. I've noticed that lacy Valentino style wedding dresses like Princess Madeleine's have become fashionable anyway, so perhaps it's just a question of lace being the 'in' thing to wear.
In regards to William's socks, I think they're either very dark navy or grey, or at least that's what they look like in the lighting of my room and PC screen.