I hate Hosteling International and I reccomend staying far far away from their hostels. I've stayed at 3 and each one was worst then the last. It seems like that can't maintain hostels of that size. If the book is a listing of all their hostels I'd buy it for just for toilet paper back up
Keep with independently run hostels. Generally
they are up kept a little better & you're likely to have a better time.
I found HI's were geared more towards families then drunken backpackers.