I spent around 5 hours playing yesterday and let me tell you, I had to force myself to put the controller down.
The variety in environments is amazing, the different routes make every race a fresh experience, the graphics have left me impressed many, many times.
Best thing about the game is the pure adrenaline rush you get racing to the finish line, trying to take the best route for your vehicle while avoiding Big Rigs intent on squishing you like a bug. Boosting through the narrowest jungle path covered with vegetation not knowing if there be a rock or branch behind every corner and then coming out and seeing the finish line, merely a few hundred meters away, look back and see all other competitors boosting to hell and back, ramming into each other fighting for 2nd and 3rd place while you cross the line.
Can't wait to play it online!