As I happened to re-watching the original Hajime no Ippo series I thought it might be interesting to briefly compare it to the new installment, Rising, in terms of both series visual presentation.
The original Ippo series aired in 2000 and was produced by Studio Madhouse. By the looks of it they were sill animating it on cells. The new series, Rising, is also produced by Studio Madhouse but as it's been over a decade since the original series it would come as no surprise to find that there's not much staff overlap between the two works.
In terms of background art, both shows look fairly attractive:
The real differences lie in the character animation. The characters in the new series have fairly wooden expressions, except during battle, where as the original characters were far more expressive:
vs.
There's an exaggerated, cartoony quality to the expressions in the original series which make the characters more interesting to look at.
In terms of action, both shows use speed lines and shading in the place of fluid animation for budget considerations. The new series also uses motion blur to imply movement which I'm not a huge fan of.
The original series also makes use of high detailed close ups for important actions which I find to be very effective:
Anyway, perhaps the most importance difference lies in the musical score and that's something I can't demonstrate in my post. The original soundtrack is excellent and I've found the most recent Ippo series so be sorely lacking in the sound department.