Watched it last night.

It looks and sounds awesome; excellent job on the sound and picture remastering.

Yes, it improves on the original cut of GF III. It straightens out the Vatican storyline and makes it a bit more understandable.
No, it doesn't lift it to the level of its legendary predecessors.
No, they don't get rid of, or seriously cut down on, the icky-poo cousin romance.
They didn't fix up some of the first half plot holes and incongruities, like Connie introducing Vincent to Michael as if he doesn't know who he is (and then, 10 minutes later, Michael is discussing how 'he's always felt responsible' for him, offered him jobs, etc etc). Still no reference whatsoever to Sonny's legitimate kids, or Connie's two sons -- all apparently victims of Chuck Cunningham Syndrome. (Sonny's twin daughters, Vincent's half-sisters, do appear, but are never mentioned in the script.)
They cut out about 15 minutes of running time, including one fairly important scene (the scene in which Connie takes on Don-level authority and orders the Joey Zasa hit).

I always thought the hate on GF III was ridculous. This doesn't fix the biggest problem, the absence of Tom Hagen -- but it's a bit more polished.