It took me about a year to get through all 11 books.
I only read when on the trains to/from work and travelling on holidays, hence why it took me so long. Mrs Eddache could read all 11 of those books with 6 weeks.
( Edd: The Unfunny Try-Hard Edgelord, Fri 10 Jul 2009, 12:26, archived)

still waiting for the last book though

( jenpots, Fri 10 Jul 2009, 12:28, archived)

It's apparantly being split in half.
Book 12a should be out later this year or early next.
( Edd: The Unfunny Try-Hard Edgelord, Fri 10 Jul 2009, 12:42, archived)

It's taken me about 2 months to get through the first book
but I've also been reading some comics. And I too have only been reading on the bus, but that only takes 20 minutes.
( SuperMatt, Fri 10 Jul 2009, 12:28, archived)