If you approach Fuel as an out-and-out open-world racer like Burnout Paradise, you'll get fed up of it within minutes because you'll have to drive a lot to get from one event to the next. But if you play through the events from the menus, while free-roaming occasionally for collectibles and unlockables, you will really start to enjoy it, without missing out on the beautiful and varied environments. Asobo have done very well to create this massive world and, more importantly, make it fun to drive around in.
If only they had worked on the vehicle controls with as much dedication, it might well have turned into the game that many were expecting. Still, it's a fun game and definitely has its moment, but with better off-roading alternatives like MotorStorm: Pacific Rift and Pure already available, Fuel is a very hard sell.