Even though it's not really jazz, it's pretty close. The instrumentation is great, and the swing and melodies help it feel like jazz, so kudos for that.
At the beginning I enjoyed that vintage-ish sound to it which really sets the tone of the piece. One thing I might have changed is the drum samples, especially the kick. I think acoustic percussion would have fit better, but the synthesized percussion gives it a unique feel. The hats and cymbals are pretty good, but the claps and kick are a tiny bit out of place.
I hear a few compression issues, especially with the piano. Make sure not to overcompress. A sign of overcompression is a strange ducking or lowering in the volume where there's not supposed to be. It's not a huge issue, but it definitely is still there.
I really like the instrumentation, as I mentioned before. The mixing is also well done. At 0:38 the mixing and instrumentation really shine. There is just enough space for everything and there are no overpowering instruments. I loved the mark tree at the transition between sections. It fits so well with everything else. The brass vibratos felt a tiny bit overused, even though they weren't. It's just the two in quick succession that creates an illusion. They fit better as accents and less as part of the music, although I'm sure you know that, as it was fine in the rest of the piece. It's not a huge issue, but just something to note.
The section at 0:55 was a nice breath of fresh air for the piece. It's also a great example of a using very few instruments while still keeping a full sound. The percussion fits in well with everything else, and everything is acoustic, which is what I was looking for a bit more in the beginning. At 1:02 the piano sounds a bit harsh for those four notes. Maybe the velocity was turned up too high or there was some other issue.
The drum fills throughout were very fitting, but I wish you had used some various percussion samples a bit more. Another thing I liked were the small stab breaks that you included in some sections. They help give the track room to breathe. One thing I might fix (again, a percussion thing) are the seven staccato notes at the end of most sections. One thing about electronic percussion is that it sounds pretty bad when it's used too much in a short space. One last thing I think you did very well was keeping the piece interesting. There's enough variation that there seems to be something new going on all the time, while still keeping the same feel. Whether it's a new theme being played, new instruments used, a key change or a combination, it helps keep me interested.
I have to hand it to you for doing something new and nailing it. Aside from a few issues, this is almost perfect. Keep working at mastering, I'm sure you'll get the hang of it eventually. Great work on this one!
8/10