what is the overall health of the plant?

Hmm, I think it looks healthy and happy. There're always new leaves growing.
That's a good sign, right?

Here some new pics:

all variegated crotons produce new growth that is green with some yellow veins/spots - when leaves mature they slowly change color. lower temperatures (60s) in the fall make the colors very vibrant, very day-glow vivid.

If your croton is permanently indoors you'll need to give it eastern or western sun for sev hours to get the proper variegation develop. Otherwise the leaves will stay mostly green.

the plant is very healthy, i don't see anything to worry about.

the growth that i see on the pic is very dense and even, the leaves large as they should be - so it's getting enough light for sure. It looks like 'Petra' cultivar.

Did you just get it or it's new growth in your care?

oh, one more - i think you were worried about that browning on the branches with spots - that is aging ;). it's a shrub, when the branch matures it develops bark, not thick, but it is wooded brown.