I've had a fun enough time with the beta, though the physics are actually not a major concern for me. GT hasn't been the pack leader there for ages, and I don't think that's ever actually been a major setback in terms of sales success. It's considered realistic enough by most, and that's probably good enough. I don't want to say it's so easy that anybody can jump in and get to grips with some of the cars — this isn't NFS, and I saw some horrifying laps at E3 — but I think PD is smart in aiming for the middle-ground, while still leaning towards sim. There are enough hand-holding aids available to make it pretty approachable, too.
My bigger concern is the penalty system. As is, it's... less than ideal, and from the evidence of the beta, hasn't really bred better driving etiquette. I suppose the argument there is that it is a beta, and people are testing to find the limits of the system. We'll see come October if it translates to the masses, then. Considering the game is being marketed as such an esports-focused title, that aspect needs to be nailed down day one, IMO.
As ever with racing games, it's a lot more fun when you're racing with people you either know, or are at least on the same level of speed and sportsmanship. I had a handful of really great races, a good chunk of them with people I met through the beta.
I'm a little sad that Fanatec wheel support wasn't included in the beta. I would've liked to get a more direct comparison between the game and the rest of the genre! On pad, it's a fair bit better resolved than GT6, though it doesn't yet match Forza for controller implementation in my eyes. In terms of physics, it feels like an evolution of GT6's engine, while rumble feedback still feels muted, even on max settings.