I’ve had an extensive opportunity to play with entity framework. Here are my few thoughts.
Code first does work reasonably well if you are starting from scratch, but managing the release of vital enterprise applications, which require care around the DB become harder after the first few iterations. So far it has been easier to retrospectively create an .edmx from the code first created database, edit it to fit the existing object model and continue from there. It helps to decouple the database changes from the code.
To be honest, in future I would be tempted to build the database first now that the tools in Visual Studio are so much better and generate a first cut at the model, kill the generation and use the generated files as a starter for 10.
Any thoughts?