Ok, guys, i got my hands on a near final build and i have a few new details for you.
First of all; lots of tracks.
Basically all the rumored ones, all the old ones (no positano long, there was 'amalfi 2' though, which is a longer and different version of FM4's amalfi, i'd say between amalfi and positano in lenght) plus at least a couple original tracks we haven't heard of yet; Miami and Rome, a gorgeous looking city track.
A lot of tracks have alternate time of day, this time though, you have a slider to control that in free race mode and you can choose any time of the day with lighting and shadows changing accordingly.
I wanted to try Spa but i was told it currently looks awful (unlit and untextured), so i tried rome instead.
Graphics are a mixed bag; slightly disappointing at first, a few rendering issues here and there, a few elements looking like a step back from fm4, but in the right places it could also look absolutely amazing.
Replays now have a completely different style; it's not floating forza cam, but not tv cam either; it's something rather unique i wouldn't know how to describe. Looked great though.
Bad news.
There's only 111 cars in the game, which is incredibly disappointing.
I didn't get to see a lot of new cars, but the Ferrari LaFerrari was there and looking great. Didn't get to drive it though.
Overall very pleased with number of tracks and time of day slider.
Wish i had more time with the game, but then my daughter woke me up.