I enjoyed the first Grid. It's definitely more arcade-y than say Forza, but it was a fun game none the less. I will be looking forward to this one.
One thing I found that the new has that I think is awesome is that there's a Chicago Street Course! 
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http://youtu.be/LhXjVXpPuX8
They also have a California Coast Course which looks cool.
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http://youtu.be/qbfuMR978GA
Do I spy an E30 M3?
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I LOVED Grid. I've been wanting a sequel for some time, but they kept pumping out Dirt and F1 games. Really looking forward to this one.
yeah I have the first GRiD, really fast gameplay and the graphics are great. with the difficulty cranked up it can be pretty frustrating sometimes!
I REALLY liked Grid. I thought it was a great change of view of racing from the tuning/crew side of racing(Forza) to a driver/owner's view of racing. A bit arcade-y but very cool in the operation/team side of racing.
Hiring team different types of team drivers was very interesting to me.
In reply to Anti-stance:
I always felt bad when I had to fire somebody. 
I have mostly enjoyed the DiRT series. 3 especially, the rally racing was quite good. I ended up playing it a fair amount today. The Michigan rally stages are really good, and I really liked Croatia in DiRT 2. I'm considering getting the DLC Monte Carlo rally, but have decided yet. Never really did any online though.
Definitely more arcadey than Forza though, but also significantly more rally.