Act 2 is the open world so many people cried for. You have to explore carefully and at first you are a bit lost, at least I was, similar to Act 1 at the start of the EA, only worse. But you can think a bit and look at the NPCs in an area and change, if they are too high.
In order to be genuinely open world it would have to avoid the level-gating that is used all throughout it, so that you could actually go anywhere and reasonably tackle things in whatever order you preferred. That isn't really possible given the way the game's mechanics and math scaling work, though.
