It's hasn't changed that much. You see that in Ruffy and Chopper. The pic of the new Ruffy looks way better, but that's because the older pic shows him in a funny pose. The tend to be much more simple drawn.
If you look at chopper it's the exact opposite. The funny and therefore simple pic is the newer one, while the older looks better.
Shanks looks pretty much the same to me in both.
The biggest change with those pictures seems to be Nami's hair.
Oda hasn't changed his style that much. The characters just get older and mature a bit.
"For Feanor was made the mightiest in all parts of body and mind, in valour, in endurance, in beauty, in understanding, in skill, in strength and subtlety alike, of all the Children of Illuvatar, and a bright flame was in him"