Obama may still hold 49% of the country saying they at least somewhat approve, but of the 50% that disapprove, 4 out of every 5 of them strongly disapprove. Only 29% strongly approve of his performance, giving an Approval Index of -11% for the strong feeling, and a -1% overall.
So, it has reached the point where a huge majority of Americans either think "Well, he's not bad" or they think "This guy is horrible."
Just think about that for a minute. If 10% more people switch to the Strongly Disapprove side, then the majority of Americans will begin to have the same opinion of Obama as they did for Bush; "Anyone but this guy!" And in less than a year after taking office.