Books to the ceiling, books to the sky, my pile of books is a mile high. How I love them! How I need them! I'll have a long beard by the time I read them!
Neverwhere is one of my favourite novels of all time.
I discovered Neil Gaiman about 10 years ago, in my late teens. I've always loved fantasy, and adored anything quirky, and Neil's books seem like the perfect marriage of these two qualities.
Neverwhere in my opinion is the best of Neil's bibliography. I've read so many stories about secret or concealed worlds that the protagonist stumbles across a gateway into, but the idea of a secret world coexisting beneath a city that is already layered in history is genius. I can think of maybe 5 other cities on the planet where this would work as well, but the uniquely English feel of this world is definitely part of its charm.
I also love how sinister this world feels. It's a world of rats, sewers, doorways, keys, and tunnels, and so you expect there to be filth. You just don't expect the muddiness of the morality of so many of the characters, even ones you come to love.
If you do read it, don't trust anyone! I'd also highly recommend listening to the 2013 audio play with James McAvoy as Richard and Benedict Cumberbatch as the Angel Islington - it's absolutely wonderful.