Act 1 is a great sandbox and the most D&D like experience as a result.
Act 2 is the strongest story and writing, much more focused and tightly built. Some cool D&D like dungeoneering/puzzles to boot.
Act 3 is what happens when you don’t leave enough time and energy to wrap it all up. It tried to be as expansive (more even) as Act 1 and they couldn’t keep up with the writing. They also should’ve done away with the entire section before you actually enter the city. Talk about a momentum killer.