There should be more, at least there were different images on patreon that people shared here, I doubt all of them belong to that boss scene. But still it would be nice if someone could share a changelog or something.
I find all new changes:
1. Second scene with Klark in house
2. Scene with SWAT after lose. Then you can get out from car or stay and see Game over ending
3. Scene with boss after lose (you can't win, he always restore health and it make bug with card)
4. New butt attack but you need play from beginning because old saves dont work correct
5. That all! Yes, he improve game texture but... i hope last update to ver. 1.0 will have more changelog and content