Forza is pretty much at the far end of Arcade racing, almost into simulation territory. It's about as far as you would want to go on a console, which keeps it entertaining.
Things that bug me about it is that all standard cars sound like they have an induction kit, take the 1.6 New Fiesta, they do NOT have that deep induction roar. Other things like take a Leon Cupra R with decent tyres and on Forza its tyres are screeching like feck at 30mph... like WTF? Dumb down the Arcade SFX guys, & the Leon does not understeer as bad as that. On the flip side GT5 sound effects are all too weak & that bloody gearbox noise!!
New game does look good though and it is great to use roads rather than tracks
Corrado in the 2nd video at 2:50 :-D