.NET ORMs - What advantage does NHibernate (or SubSonic or whatever) give over using Entity Framework?

I'm wondering, what are the main reasons for not to use the built-in Entity Framework?

I've read that it's disliked because of its bad implementation, but is this all? And is it still true? (I don't remember the publish date of the article)

I know there exist a lot of options, but why should I consider switching? I only have a little experience with EF, and I can't find any good arguments for what to use when, or why (not) to use whatever.

From stackoverflow

• Have a look here, any other specifics give us a shout

  http://stackoverflow.com/questions/517600/when-not-to-use-the-entity-framework

  l3dx : Thanks. I DID do some searching before posting, but obviously not enough :P