As a developer ORMs can be a real benefit, they can speed up development time significantly, and they offer a proven, standardised structure to your data access layer, if used well you can even write code that is database agnostic.
But in some ways these are also the problems.
Developers no longer have to worry about what is going on at the database level, and I hear a lot of DBAs complaining about the use of ORMs, how they aren't good for the database and make a DBAs life harder. I feel I have a fairly good understanding of what some of the problems are (query plans etc.) but what I'd really like to know is: