The areas of Google App Engine that I would to improve or enhance include its allowance for complete end-to-end deployment and scalability; however, it is manageable only for a few languages. For instance, it doesn't support languages C and C++, only basic support for Node.js, Java, and Ruby. It's not a comprehensive solution for all scenarios. Moreover, the security feature is based on IAM roles, but it should ideally be based on Active Directory (AD) roles. For IAM-based roles, we need to add the proper users and provide all security permissions manually. In an AD-based model, we would simply add users to a specific group, and all permissions would be inherited.