Well, the way I see it Cameron was right to oppose what he opposed regarding the financial market regulation that would have put London at a competitive disadvantage to New York, Shanghai and Beijing with regards to financial markets. The way I see it, based on what has been publicly said, I think his position is eminately defensible; he clearly had some non-negotiables, so did Merkozy, and they couldn't come to an agreement. I don't see any kind of metagame going on here or anything...although I am literally on the other side of the world.
I don't think, however, that it is in the UKs best interests to leave the Union all together. Clearly, a large propotion of their trade goes to the region - and although this would be unlikely to change were they to exit formally, any barriers would harm flows. I don't know how the migration system works, either, but presumably the UK would be a beneficiary in terms of attracting and retaining top talent?
The real issue for me with regards to Europe is the fact that you have 26 different cultures (vastly different, not like Western Australia/Victoria or New York/California different), 26 different fiscal policies, 26 different industry policies, etc, but one common monetary policy. This just does not work without tighter fiscal integration, which would mean Germany, France and the other fiscally stronger nations (say, the Netherlands, Sweden) transferring fiscal capacity out of their countries and into the weaker nations. Either than or you hope and pray that internal migration of labour and capital sorts out the mismatches in productivity, capacity and growth; which I can't see happening due to the cultural barriers.