Wow, this is impressive! Though I've come to expect that from you. 😉
Definitely my favorite parts are the moments with the 1st 'fugue' theme, I really love the intensity and polyphonic effect those sections create for me, especially the opening. In fact, this is probably one of the first successful uses of this fugal-opening effect I've heard so far, as I notice a lot of them tend to be overly sarcastic and ironic, or just boring, as far as my personal taste goes. You made it straightforward, flowing and instantly appealing! Also, I don't really have a least favorite part, as I've enjoyed the piece the whole way through!
There were some little parts in the waltz section I was mildly bothered by, but nothing significant; just some tiny details in the bass line and countermelody, but it's fine as it is, unless you would like me to elaborate. Otherwise, I enjoyed basically everything.
I think it's very effective, I really enjoyed the structure!
There are a couple of pieces I was reminded of, the 2nd movement of Rachmaninoff's Symphony no. 1 and the 3rd movement of Hans Rott's Symphony in E major. These are both the "Scherzo" movements of the symphonies, as can be expected. Both are brilliantly orchestrated, and quite underrated, especially Rott's symphony. I'll link the pieces here:
Another high-quality orchestral work from you! I wish more 20th-century symphonic scherzo music sounded like this.