Speaking as an Avid fan of the real life series I have to say these seem really rather good - who-ever has stepped in to help the mod team out with the physics has done a sterling job.
I've just done a session at the new Sandown (Even if we don't use the V8's we need to use this track
) and all 3 cars on a fairly stock setup are lapping within 10ths of each other.
They accelerate, corner, change direction and pop up onto 2 wheels over the kerbs pretty much just like the real things.
From a championship point of view though, they are also evil buggers to drive just like in real life - they have no ABS, traction, stability or magic - so you've want at least 1 fun race to see if people are up to the challenge. Given some of the grid levels in the Lotus championship I think this is something to keep in mind.
If I have to criticise anything it's the sounds, they're not bad by any stretch of the imagination, but they're not quite right either.