Suntek's Motocross is a competent vertical racer of the "infinite random opponents on a procedurally generated track that never turns" variety, but it stands out in two respects.
First, the motocross cycles are large on the screen without making it hard to react or navigate. They're a little squat, sure, but the size hits just the right point on the maneuverability vs sprite size slider.
Second, the gameplay format is mixed up every so often with a field of obstacles you need to navigate. This isn't exceptionally meaningful or difficult, but it's a nice variation in the gameplay.
So, much like in Activision's Enduro, the goal here is to pass X number of cars in a given round. If you hit an opponent or the side, your speed is reduced and you're passed by a number of other cars, giving you more you need to speed by to pass the round. The limiting factor here is your fuel, which continues to tick down as you go.
Then you have the obstacle fields I mentioned – hit a pot hole, pool of water, or what I assume are rocks and you'll start to wobble until you manage to grab one of these flags. As I've said, it's a welcome variation, but a little frustrating – you don't really have a way to end this faster, and it just gets in the way of finishing the next round.
Downsides? Well, after a bit you notice that all the opponent bikes are traveling in formation at exactly the same speed, making them obstacles rather than foes to contend with. And the sound is just the sound of your engine. I did appreciate the little animation of your tires at the front and the back – there's not a lot you can do with Atari sprites to make them more interesting.
I was tempted to give the game a B rating, but the uniform speed all the other bikes are moving at and their lack of horizontal movement knocks the game back down to a C+. Good for a few minutes maybe, but I can't see wanting to play it for long.