Haha, it's nice you added your voice, even though it can only be heard twice in the piece. Those little sparks of creativity are always nice to hear when I listen to something new. It doesn't sound unprofessional at all, and I'm really surprised it turned out that well, considering you recorded it with a headset!
I really like the composition. There's a lot of variety and the arrangement makes sense. The only thing that was a bit disturbing though, are those 'big drum' samples you used, specifically at 01:00 - 02:10. The infamous 'machine gun effect' is quite apparant here, so I suggest working with different velocity layers in the future (for all instruments, that is). True, it adds quite a bit of extra work, but the result is well worth it, and makes your production sound more natural and realistic.
The mix in general is decent enough. The only 'problem' I could find was with, again, the 'big drum' samples. Cutting the higher frequencies here might have been a good idea, as they tend to sound a bit too sharp compared to the other instruments.
All in all, a very well written piece! I'm quite curious to see what future productions you'll bring us.