1) I love that they keep that little girl that he first saved in the story as a reminder to how far he came
2)The use of the smoke surrounding him and giving it "soul like" mouth and eyes akin to the souls lost to kaiju over the years was an astounding choice.
3)I am quite happy that I was wrong and they DID choose to give him a form change. This imo is the best choice to include a power up/design change/etc imo. The use of the living kaiju in his body and the foreshadowing was really well done to not use it to the max.