.. the smoothness of the central seconds hand (amoungst other things!). i.e. it runs more fluidly on the new model and less choppy (which was an issue with the 5002.
personally, i like the new dial design. i think it suits the watch and makes it more cohesive. I like the tiny bit of red on the PR too. dont get me wrong, the old design is very nice too, but the 04 just does it MORE for me.