The Government Accountability Office has released its findings on whether or not agencies were complying with FOIA requirements. The study, found here, dealt with various FOIA requirements and various agencies. It's interesting reading but it doesn't really make any finding that frequent FOIA requesters wouldn't already know. Meritalk discusses the study here.
One of the things I think is important is that while agencies have implemented the requirement that they have a dedicated phone line or website on the status of requests there is no requirement that the phone line is answered or the website is updated on a regular basis. I would argue that without a call back within one business day or a weekly update to the website, some agencies have not followed the spirit of the law in that aspect of the FOIA. Another interesting finding is that on backlogs. It is my belief, that without the blessing of those at the top of agencies. FOIA offices are really unable to attack backlogs in any meaningful way.