Hiring a Google App Engine developer can significantly enhance your web application development process. They can effectively leverage Google's powerful cloud technology, ensuring high scalability, performance, and security for your applications. With their expertise, they can manage large datasets, perform complex queries, and maintain efficient traffic management. They can also integrate various Google services like Google Maps, Gmail, and Google Analytics. Their skills can reduce infrastructure costs, accelerate deployment, and minimize maintenance efforts, leading to faster and more efficient project completion. Therefore, they can provide a great value addition to your team.