Right away, the pizzicato at the beginning sets the song off on a bit of a mysterious path. I love how the song is laid out in very distinct sections. I would not necessarily say that the song has a slow build-up, but I would say that the song builds tension over an elongated period of time (or that is how I see it).
Overall, the transitions are fantastic (even though the actual transitions happen later in the song). The section at 2:01 caught me by surprise a little bit, and it is also my favorite part.
Keep up the great work and I hope do another review sometime!