The Grim Dawn Early Access on Steam now includes Act II of Crate Entertainment's role-playing game. This announcement explains what this includes:

We are pleased to announce that Act II, roughly the second third of the full release, has been released to the public!

This release should just about double the available content and raises the level cap to 35. There are many general improvements, including the redesigned HUD, some graphical enhancements, loads of new items and insidious quests.

In summary, you can look forward to:
106 New Items!
23 New Bosses and Mini-Bosses!
17 New Quests!
10 New Enemy Types!