I agree with this reply and will echo with my impressions.
My demo impressions. Keep in mind I have greatly enjoyed the Forza series. Forza 4 and FH2 have been my favorite. Did not enjoy F5 much at all. Considered F5 more of a demo. With that said here we go.... Long reply ahead.
First impression of Rio in the Ford GT. Wow what an incredible looking track. So lifelike and absolutely loaded with stunning color and detail. Honestly I found myself so overly distracted by looking at how much color and how alive that environment felt. This will be a dream in photo mode for sure. Most sim tracks seem to feel a bit bland with very little in the environment since the main focus is generally on the track. It really felt like I was in a real life race in front of the entire world watching me. I don't recall ever feeling anything like that in a simulation racing game. Simply exhilarating!!!
Physics and most of the audio have improved over F5. The engine audio still seems a bit toned down even with music off and in game audio all the way up. I am in 5.1. As mentioned already, would be nice to adjust individual engine audio. The rest of the audio is fantastic as other members have covered in detail. Fireworks popping on specific sides, curbs, ambient audio and much more.
Lime Rock was where I finally got to sink my teeth in and remove assists along with adding manual with clutch. I grabbed the Subaru Impreza my first time, grabbed the Nissan my 2nd time. Last part of the first corner caught me by surprise a couple times and I went wide. Instantly noticed sticky grass is gone and still perfectly punishing. You go off, you will regret it and will have to make up time for sure. Overall enjoyed this new track.
Wheel spins. I absolutely love these in FH2 and of course love them even more in F6. They remind me of the earlier days of playing the GT series. Specifically the moments in GT3 where you finish a series and see 4 silhouettes spinning on the screen sitting in anticipation wondering what prize you earned. Wheel spins give me a euphoric flash back of that, and I love it!! Oh I won the Veyron and 1 million.
Yas Marina night. I am a huge fan of this track and truly enjoyed seeing it at night. The night racing was wonderful. Dang near perfect IMO. NOt too dark, not too light. I really liked finally seeing the lit up hotel finally....with lights. Unlike F5. Would like to see the light glow a little better onto the track and cars as they drive by, but it was still beautiful and I truly enjoyed this track at night. I couldn't tell after a few laps if it looked better than the F1 games but it still looked great.
F1 race on Indianapolis Motor Speedway. I enjoyed this track and the F1 car. I also liked the announcers detail about how the entire track used to be made of bricks. Now only a yard strip remains.
Finally, Sebring in the Rain. Mother of god this was simply incredible!!!! My fondest memories of rain racing were in PGR4 and the F1 games. This is by far the best I have ever experienced in a racing game. The audio, visual effects, and the physics of the puddles were dang near perfect IMO. The puddle physics were terrifying in a good way. I absolutely loved racing in the rain. I have never seen Sebring so alive. Every crack and bump detailed with water. Can not wait to see the other rain tracks.
Demo Conclusion. Long reply but dang what an absolutely impressive demo. This is easily shaping up to be the best Forza of the series. So glad I purchased the digital ultimate edition. Cant wait until next week!!!!!