I enjoyed it! We also used "billboarding" with our MC and it definitely adds it's touch in a 3D enviroment.
Main points: The use of sound is generally the fastest way to tell the player that something actually happened (i.e hurting the boss), so focus on that in the future. VFX was nicely used, try exploiting it a lot more for it's both cheap and "juicy". On my screen (1920x1080) there were issues with the tilemapping, which displayed some of the white edges. There were some enemies that were invincible too, not sure if a bug or deliberate. The easter eggs made me chuckle and are always welcome.
Congrats!