Both books are amazing and I recommend them highly. Since I've written about The Book Thief in previous posts, I'd like to focus entirely on World Book Night. I'll write a separate post for City of Thieves.
First, if you haven't heard of World Book Night, it's always celebrated on April 23. April 23 is Shakespeare's birthday as well as Cervantes's birthday. It's a chance to celebrate reading and all the pleasures that it brings as well as a chance to promote literacy. On World Book Night, volunteers give out 1 million copies of books to "light" or non-readers to encourage a love of reading. With all the different types of entertainment available nowadays, folks are less and less likely to grab a book to occupy themselves. It's such a pity because it's almost impossible to express the calm and escape that a wonderful book can bring. I think that there's nothing like it.