Comments are spot-on. The 599 is very large whereas the Vantage is much closer to Gransport in size and feels much more usable on the road. Also true about the engine sound/feel ... the 599 sounded angry, revs higher. The Vantage is somehow more refined and "sweeter" (if that makes sense?)
The 599 does have a remarkable trick suspension (magnetorheological) which can cleverly disguise bumpy side roads when at low speeds.
But so far, despite the entirely different history, the Aston feels to me more like the natural successor to the Gransport - the Ferrari was just too extreme in many ways to use as a road car.
If you want to see more of the Vantage the sales video is still up on youtube. Mercury Silver with Obsidian Black leather:
https://www.youtube.com/watch?v=RFSSRxqmcRE