Danny Simmons has a post on why to use Entity Framework.  Here's my main gripe with Danny's post and all other such posts on EF.  Microsoft keeps waxing on about how EF is so much more than an object relational mapper, but in reality it is still so much less than nHibernate, which has become the de facto standard for O/R M.  So how can it be more when it is less?  I understand that Microsoft has a grand vision, but Microsoft always has a grand vision and it only gets realized some of the time.  (Need I give countless examples?)  Additionally, there are often times when Microsoft's grand vision doesn't mesh with what the last 20 years of OOP has taught us!  Why do you think the nHibernate people (that includes me if you haven't guessed) scream so loud about POCOs (among other things)?  Because they know that the rest of the programming world has already learned this lesson and they are terrified that Microsoft is going to make a series of critical mistakes that lead the platform and its developers down a wretched path.  Sometimes Microsoft reminds me of people I knew in high school and college.  They are really smart, but when given complex assignments they wouldn't bother to read the project guidelines or pay attention to the teacher's instructions.  Thus, they failed, in spite of their grand ideas and brilliance.