My bet is that there will be problems with timing, distribution and the method of actions, it'll be mostly effective for most of the people. It'll just arrive too late, we've got what, 12K cases already, and there is no deployment of vaccine yet.
Sure they've ordered enough for the winter, but if it isn't deployed within a month they'll have missed their main opportunity. What is strange is the rate of spread in the UK. It'll be a bit rubbish if the nurses who have to give the jabs can't go to work as they're at home sleeping off sympthoms of swine flu.
Still its good training for when a proper nasty flu arrives, one that actually kills a high % of those infected, as an eventual bird flu might be. Can't wait until they start taking about 'lessons learned' and other such spindoctoring.