I got a chance to play some Forza Horizon, and the major differences between this spin-off and the original series I noticed were:
- Frame rate has halved from 60FPS (Forza 2,3,4) vs 30FPS (Forza Horizon), so the smooth butter feeling is gone, although not all players may notice this
- The cut down FPS allowed for much much much more graphical horsepower, for amazing foliage, backdrops, effects and pretty much everything was improved
- The game has shifted from a simulator to an arcade like game
- Scoring system is the total opposite of the other Forza games, driving like a drunk is actually rewarded with extra points
Here is some video footage of the gameplay, alongside my commentary: