George Hamilton was a terrible replacement to Duvall's brilliant portrayal of Tom Hagen. It would of had been interesting if the writers actually did something with Hagen's son instead of having him popping up in some scenes and eventually disappearing forever.

I think one of GFIII's weaknesses were the characters -- they had so many characters but so little time for organiziation! If they had made the new characters interesting and used them throughout the film, I think we would of had been surprised what GFIII could of became.

But personally, it is quite a loss that Hagen wasn't in the script because Duvall wasn't interested. I don't know if it could have saved the hate to the film, but maybe a little, I guesss.