Just from the video you can gather that there's much more than just a visual upgrade. The fact that you can apparently just rob random stores, that there seems to be specific ways to open cars (so different cars, different difficulties?), the variety of activities, and the pnjs that seem to remember you, etc. I was afraid it would not live up to the hype, but now I think it just might

If you live in California, this is excellent training. You can totally train in GTA, and then graduate to lawlessness, rioting, and looting stores in real life.

https://youtu.be/-M8xzVFQ84U?si=HWw89pSW7JD7PWeF