I'm a little bit disappointed. After expecting so much from the new game on the new console, its a kick in the face that Forza 5 was rushed out as a day one game to help sell consoles. Too much content cut out and resold as DLC, too many features asked for since Forza 2 that haven't been implemented, way way way too many bugs and errors that show it up as an unfinished product, and a focus on graphics at the expense of content. You ooh and aah at graphics for only so long, content and gameplay options are what ensure a game's longevity.
That said, I'm hopelessly addicted to Forza and will no doubt spend countless hours playing it. The new physics engine is great, except cars seem WAY too tail happy, the Drivatar system is an interesting take on AI.