At this moment, this is my favourite resource for warlocks. The patrons are well-balanced, thematically appropriate and unsettling in a Lovecraftian style that'll leave the other players at the table saying "You made a pact with a what?..."
The extra invocations and pact types are a great addition too. Even down to the little touches such as each power's name, this a brilliantly constructed piece of work. The cherry on top is the unique art. My favourite patron (today): The Deep One - a clever way of making an underwater patron still relevant on land.