i think it does good to customers.meanwhile ,it will prompt the two company to improve their products.
Firstly ,from the Ads ,we can judge which product is more high-quality and useful ,it becomes convenient for customers to make their choices.
Secondly,because of the competition ,both of the companies will enhance the qulity of their products in order to defeat the other or at least have more advantage in the industry.The result is through the competition ,they can reduce their cost too.