It's an absolute nightmare, and in a rare moment of sympathy for Cameron I don't see what else he could have done because he's screwed either way and he knows it.
I don't think being in would have necessarily been brilliant either, and I don't think for one moment a new EU treaty 100% fixes anything (the US is basically the closest model, and that's hardly financially rock solid just now). But I can also see the worst case scenario coming to pass: a referendum, a hijacking of the vote by the vested interests of the few at the expense of many, and the UK becoming increasingly isolated and with a further weakened economy.
Plus of course as soon as we left the EU, the next demand would be made - foreigners out. Then the witch hunts start.
We're kind of fucked either way. Cameron's "interest of the country" is really the "interest of the Square Mile", but signing up to a hastily put-together and foggy treaty which has predominantly been written by the Tory equivalents in Germany and France is not particularly appetising either. It will be interesting to see if all the Euro bankers from Paris, Frankfurt etc all abandon ship and seek asylum in the Square Mile.
I'm wondering if getting Britain out of Europe is being orchestrated as Cameron's "Falklands moment". Nothing like a bit of jingoism to capture the right-leaning working-class vote, whilst simultaneously giving them an economic kicking. It worked for Thatcher, Reagan, and Bush.