Question

Question for everyone: should I just keep writing and revise everything when I'm done, or should I revise chapter twelve now and post a hopefully more exciting version? Please give me feedback on this.
Now I will attempt to hone my skills with an irrelevant practice action sequence:

Mortimer looked down from his flying gazelle at the herd of attack Guinea pigs who were pursuing the Queen's 1967 Ford Turino. He knew she would not last very long if they caught up with her. He had to act. He urged the Gazelle forward. He could feel the wind on his back as he closed in on the guinea pigs. Suddenly, one of them caught sight of him. It squealed a blood-curtling squeal and jumped into the air. The other oversized rodents turned to face him, hunger burning in their eyes.
They all began to jump into the air. One of them grabbed the gazelle's hoof. His mount furiosly beat it's wings, trying to escape, but it was caught fast. Mortimer looked down at the ground moving below him. I wasn't that high up. He could probably survive the fall. Another guinea pig gabbed the gazelle's hoof. Under the combined weight it plummeted to the ground.
Mortimer jumped off it's back, drawing his peanut-butter-covered mace as he hit the ground. The sticky bludgeon felt heavy in his hand, and the smell of Jiffy (tm) mixed with the smell of blood in the air. Mort looked around. The gazelle was struggling to free it's legs while trying it's hardest to impale one of it's assailants. But the rest of the creatures were fast closing on the queen - and getting away from him. With one last glance at his embattled companion, he hoisted his peanut-buttery weapon into the air and ran towards the herd of guinea pigs.
He was running faster than he had ever run before. He could barely breathe now, but all he could think about was keeping those monsters from getting to the queen. Finally he closed on the guinea pig at the back of the pack. With a final burst of strength, he threw himself onto it's back.
The confused animal looked around, trying to identify it's attacker. At the same time the peanut butter was doing it's job - it's enticing smell had begun to lure the guinea pigs away from the queen. Turning away from their pursuit, they approached him, slowly, letting off low, menacing purrs. Seeing himself hopelessly out-numbered, Mortimer realized he had only one option. He removed the small, avacado shaped projectile from the top pocket of his vest and hurled it with all his might into the air.
As the avacado flew up, time seemed to slow. He could see each guinea pig breathing in and out. He could see exhaust slowly emerging from Her Majesty's tail pipe. And as the avacado reached the apex of it's flight, time stopped. The fruit opened up, and out stepped Franklin Pierce.
"Hello, Mr. Lima Bean," said the former president, with a snicker, "I see you've finally taken me up on my offer. I just hope your prepared to pay the price!"

So, give me specific feedback on that, and I will improve it accordingly. Then I will try to apply that knowledge to my story. Since it will entail many major action sequences in the near future, I felt this was a neccesary step.