There are different schools of thought on the Godfather restoration. Some say that the older DVD release is a more faithful representation because it was scanned straight from an actual print and dumped onto DVD, without any fiddling around.
For the new set, they put the original negative into a computer (which was not color corrected) and adjusted the colors, contrast, etc. to best approximate how it would have been color-timed photochemically. They blew out some whites that were definitely not blown out in the original, and fixed the scene where Michael guns Sollozzo and the policemen down, which was grainier in the original release because of a printing error in the lab.
Also, the early DVD's have the original burned in subtitles (because it was scanned right from a print), but the new restoration has differently formatted, player-generated subtitles.
BUT, the restoration is good because it has the original mono version.
What I want to do sometime is synch up the mono mix from the restoration with the earlier DVD release.