I finished Book 5, thus finally completing the journey.
Technical stuff out of the way first: the latest update revamps the entire Dreamfall Chapters. The game looks and plays better overall. There are a lot of significant engine improvements, better lighting, rendering, and they tweaked in particular with Book 1 to improve performance in Europolis. Apparently, they also reworked some scenes in Book 1 to improve gameplay and the way the story unfolds.
With regards to the story, it was an interesting journey to say the least. It had a few surprises and some nods to the earlier games. It was nice but not groundbreaking in anyway.
A lot of the game's story felt like with each episode the developers played on the fan reactions rather than staying true to their original intentions, which is not necessarily a bad thing. It's nice to see something evolve over the course of two years playing it. That said, the episodic format didn't really do it for me. Waiting several months between Books (episodes) really killed the story's excitement. I suppose I could have just waited until all Books were released before I started, but c'mon, Book 1 was released in 2014!
If anyone has been holding out to play, now's the time. The game looks great and runs so much better. Plus now you can binge it rather than wait months between episodes.