Create and Update can be particularly difficult as it might need other data to guide the user.
For instance on my example site the create/update of a Post needs the user to select the right Tags and, in my example, the Author (try and then edit an entry).
That needs extra data, which is where Data Transfer Objects (DTOs) come in.
I am a strong proponent of DTOs I have used them heavily and I find they really help decouple the data and business layer from the UI or Web Api.
Having decided that the Repository/Unit of Work pattern does not add anything to Entity Framework (EF) the question was how to tame EF to work with Domain-Driven Design principals.