The original AC was good for (imho) it's road feel and huge quantity of user content like tracks, cars, and mods (SRP and LA Canyons are great.) The overall product itself was really amateurishly produced IMHO (eg. shitty launcher) and inconsistently polished, although everybody looked past that because the in-car experience was better than anything else at the time and the mods make AC a blank canvas. Whatever you wanted to get out of AC, you could do with mods, and there's no other racing game with that flexibility. That's why everybody loves it.

The broader physics in AC never really did it for me, as a Dirt Rally fan. BeamNG is at the cutting edge of physics and playability, and going back to AC physics from BeamNG is pretty tough. That said, I am super excited there's a new rally game and will definitely pick this up if it's half decent. With a little love, I'm sure they could do a make their physics model feel decent for rally. I hope they have some decent damage modelling because AC's poor damage modelling made even tiny impacts totally unphysical (imho).

(I haven't tried AC Evo or AC Competizione though so it's possible the physics model has been improved... can anyone chime in on that?)