I certainly expect the fall elections to be a better indicator of where Obama stands in approval. Again, some of it has to be midterms and the honeymoon is over effect. Polls do matter. It seems the ability of the President to accomplish his agenda is tied heavily to approval with the public.
i think the midterms will be interesting. but again, both clinton and reagan had huge problems at the midterm and both were re-elected handily. no president with an approval rating of 47% or better has ever lost re-election. But you're correct that poll numbers to in some cases affect the ability to get things done.
but truthfully, he got a huge amount of big legislation through early on and i think those battles absolutely affected the poll numbers. but, in my opinion, the fact that the right started with the 'ihopehefails' mantra the day he was elected and that din has kept the numbers largely divided between the people who voted for him and the people who wouldn't have voted for him if he were the second coming. the minor fluctuations are probably the centrists who vascillate depending on the issue. it's also true that a lot of the criticism comes from the left which thinks he is too centrist... but they aren't going to vote for a rightwing candidate.
so all in all... politics remains a full contact team sport.