Over the past year or two, I've been a casual observer into the Entity Framework coming out of Microsoft. Being an ALT.NET guy, the world tends to revolve around NHibernate for me so I've already got an excellent OR/M tool in my toolset. One of the big issues with EF that we've recognized is the general direction Microsoft has taken with it, following a data centric model rather than an object one. One of the first principles I picked up when I started doing OO programming (back in the SmallTalk days in the 80s) was that objects are defined by behavior, not their properties. Yes it's true that objects are pretty thin without data, but data is not my centre of the universe.
What we see on the horizon is a new breed of VB6 drag-n-drop programmers embracing EF as the next Messiah. We see a new generation of developers focused on mapping their data models and missing the target of architecting and constructing well designed systems. As a result, the community has put together an open letter to Microsoft outlining these concerns. The letter outlines the deficiencies in the EF specifically related to the values we see as solid working practices. It's late to the game and Microsoft probably isn't going to make any sweeping changes so close to the release so don't expect any big short-term changes however as Dave Laribee says, it's good to be explicit and professional about criticisms so this is one of those.
What's interesting too is that Microsoft has put tgoether what they call the Data Programmability Advisory Council, a team of notable people including Eric Evans, Martin Fowler, and Jimmy Nilsson (all very non-data centric guys in their own right). I'm not quite sure what they will do or how they fit into the entire fray but it might be a step in the right direction (whatever that direction may be).
You can view the entire letter here where you can sign at the bottom to show your support and you can view the list of signatories here.