Here's poll analyst Nate Silver on Obama's (slight) approval rating dip since the oil spill:

Although the trend is not very robust -- it may just be statistical noise -- the notion of some modest downward pressure on Obama's numbers rings true to me. On the one hand, this is a real event, a really horrible event, that real people are noticing -- and not the sort of ginned-up faux scandal that can dominate Washington's coverage during slow periods in the political cycle. Although it's dangerous to relate from personal experience, a lot of people in my social circle have certainly been thinking about the disaster in the Gulf, including what they perceive to be a lackluster response from the White House.

On the other hand, it's not exactly clear what the critique is. The most widespread criticism of Obama is simply that he's expanding government too much, too fast (in other words, that he's too liberal). In the case of the oil spill, however, the prevailing sentiment seems to be that Obama was not quick enough to get the government involved, and was too deferential to BP. I don't mean to oversimplify this -- I recognize that there's a perfectly coherent intellectual position which holds, for instance, that deficits are a huge problem, but also that the White House needed to intervene more forcefully in the Gulf. Nevertheless, the criticisms have been somewhat orthogonal to the usual ones that the Administration receives.