Biggest drawback for me was having to use VTL to write my resolvers. Normally, I wouldn't mind using a template language for UIs, but not for business logic. This isn't Amplify's fault. They use AppSync, which made the design decision to use VTL. Until AppSync adds support for TypeScript, I wouldn't consider using Amplify toolchain to start a new project.

As an aside, you can still use Lambda resolvers rather than pipeline resolvers, but that's tedious to set up and it's also more costly than pipeline resolvers.