I absolutely don't want to defend Obama on the topic of government transparency, since this is an area where his campaign rhetoric and his actual behavior could hardly be farther apart. I didn't vote for him in the primary, in 2008, but I came close, and the biggest selling point he had, for me, was that he was the first presidential candidate I'd ever heard put the goal of government transparency so prominently in his stump speeches. I was never an Obamabot, expecting him to fix Washington and lead us into some post-partisan age, but I genuinely did expect him to foster a meaningfully more transparent and accountable government than Bush did. And, instead, you could make a very strong argument he's created the least transparent administration in history.
Having said that, though, the backlog of FOIA reviews could also have something to do with government austerity. Since Obama's first month in office, the number of federal employees has decreased by 2%. Meanwhile, the population has grown by about 5%. So, we'd expect about a 5% increase in the burden on the government, other things being equal (including about a 5% uptick in FOIA-review workload), and yet 2% fewer people to carry that burden. The expected result of that government austerity would be poorer government performance, including longer wait times for FOIA reviews to happen. There's no such thing as a free lunch. When you downsize the government even as the population grows, you should expect worse service.