I've so far completed up until the Caribbean. I thought it was great! I've been reading already a few posts saying Caribbean was the worst of all the worlds. I was even super into looking for the white crabs. The island exploration was great too I felt.
I really dig Caribbean as well, love the open ended nature of it. I just kinda wish they did more with Port Royal since it's absolutely beautiful, I kinda feel the same with Corona as well(I'm talking about the kingdom, not the world of Corona itself).
Caribbean also seems to hold up really well frame rate considering how gorgeous it looks.