The problem with III is that the storyline is too forced. II uses the backstory of Vito's early life which was part of the original Godfather novel, with the plotline of Michael's being the Don in Nevada being a logical extension of the "move to Vegas" they discussed in the original.
I think I am correct in saying that at the time of III FFC and Puzo may have needed the money, and unlike the original, III was something the studio wanted instead of it being something the director wanted.
I believe Wynona Ryder was slated to play Mary, but became ill at the last minute, and FFC made the terrible mistake of casting his daughter, who is a talented writer and director for sure, but no actress. The casting of Hamilton was a bit of Hubris also. I think FFC thought he pulled off a fast one by casting Troy Donahue ad Merle in II, and was trying to duplicate it.
For my taste Pacino overracted. Eli Wallach was just awful.
Standing alone it would be a 3 out of five star movie... along the lines of another mediocre but entertaining Pacino turn in "Devil's Advocate." Nothing more.
If there is anything good in GFIII its the acting of Talia Shire.
FFC didn't want to do Part II initially. He relented when the studio gave him total control.
Part III was a cash grab. It financed his winery.
Had Rider and Duvall been a part of Part III it would have instantly been much better...but it still had a weak script and was made too long after Part II.
