Part of the attraction to ORMs is that you just define your classes and essentially freeze-dry and thaw objects with a couple of lines of code. The problem her

Part of the attraction to ORMs is that you just define your classes and essentially freeze-dry and thaw objects with a couple of lines of code. The problem here is that you stop thinking about your data as an independent thing that must be designed for long-term persistence. Code itself should be mutable, easily changed and modified. The on-disk data is the opposite of this -- it must be iterated on carefully, and its requirements must be clearly defined as to be supported in the long-term. I'm very wary of tools that do not make it easy to explicitly and rigorously define the data model entirely separately from the object model that will be used to represent it in a specific version of one application. I think tools like LINQ are valuable because they make working with relational algebra and projections cleaner, but do not abstract the fact that you are working with a long-term persistent data store that is not the same thing as your comparatively short-lived object graph.