The 'historical' Spa Francorchamps" course is one of the most iconic courses in racing history and a venue in which many accidents and deaths occurred -hence why the "new" Spa course emerged from the old one, sometime in the late 70s or early 80s.
For modern vehicles, this is a fast and somewhat easier circuit to race on.
To what extent or not this mod/rendition of 1958 Spa is accurate -- this circuit is very bumpy for the 'better' in my opinion: It makes this track a little more challenging and fun than it would otherwise be and gives it some personality.
Graphical textures throughout the entire circuit are superb; the course has very many off/near-track objects (hay bundles, pedestrians, houses, cows, etc. etc.) all of which look very realistic. The surrounding alpine scenery is extremely verdant, lush, realistic looking and dark green which makes the racing experience that more authentic and satisfying.
On minor complaint is that the ambient lighting throughout the entire course is somewhat too unnaturally and unpleasantly dark -- even though the skies are bright blue and there aren't many clouds -- as if one were racing in the early dusk instead of the middle of the day...