I thought this would be a lot more painful. Try to watch someone else adjust something - you think more, more, less, no stop, no, too far. Go back. No, the other way. No, the other other way. On a zillion parameters.
However, there are computers involved and a thing they attach to the screen to micro manage the color setup.
Net result: the tech said it's about 35% better. Less blue. More accurate color mix and less enhanced sharpness, which adds distortion.
In high sun even with the shades pulled, enough light was entering the room to make it hard to judge for sure how it'll appear in normal nighttime use. But the little bit I saw was impressive, if a little subdued compared to what we had (which was quite a bit too high/bright.)
The sets ship with a vivid setting which was about 4000 degrees Kelvin above normal (my choice out of the box) which was another 3000 degrees above the ideal of, I think, 6500 degrees. (These are light measurements, not heat.)
So we'll get used to the look and report back after some time passes.
On our old set, years ago, the ISF calibration really changed a mediocre picture to a good one, often surprisingly good.
Starting now with a high definition picture, any improvement will be a real eye opener!