Honestly I don't see how the EF benefits a large, complex fat-client app with a data store that has hundreds of tables ( thousands of columns ). If you have to generate a CSDL file for every combination of entities you plan on querying back then you have lots of work ahead of you compared to someone with good meta data on their data store ( relationships etc.. ) and generating queries in code and submitting them via good ole' ADO.Net. The someone who has to generate those XML files still has to know the relationships in the data store.

My .02 worth from what I have implemented and read. I think EF will only benenfit web apps or small concise apps that try to convert their limited amount of tables to objects not very big enterprise apps.