Great job! Let's see, as it's a full theme with no clear boundaries, I'll go ahead with my impressions as I felt them:
At the beginning, the melody somehow took me to a hospital sick kind of mood, maybe distantly reminding me of the beeps of the vital signs of a patient about to die. Loving the glissandos and the sound design of that brassy delayed synth. At this part I started to lose a bit of interest due to being only two melodic voices with no clear direction and no percussion or bassline. Then the rhythm base I was expecting appeared, but I felt it was a bit too in the front, maybe lacking some reverb after my ears being used to the previous deep delay of the leads. I felt the kick specially to be very near me.
There was a bit of a pause here, and I really digged the new percussive hits with echo. Here there was a point when there was a bit of an abrupt change into another section, which felt a bit harsh. The trance like drums work fantastically well here, and I am loving the interplay between low and high register mallets. Very organic incorporation of the Dies Irae, which works great until the last ending part, when it starts to maybe feel a bit more random.
Overall, the piece set me in this dynamic and a bit disturbing mood, with those out of reach melodies and percussion runs. It was very interesting to listen to and I appreciated specially the sound design of the hits and leads.