Obama's next abject surrender is only months away, if that. When the trigger in the plan comes due, he will agree with the Republicans that there can't be big defense cuts, and they will get their way on the rest once again. Meanwhile, there will presumably be a government shutdown surrender on his part before the end of the year.
Even if he wins the 2012 election, it seems obvious that he will capitulate again on the Bush tax cuts (and of course he ostensibly wants to extend all but the top bracket cuts, although that too I take simply to be timorous advance surrender dating all the way back to 2008).
Two points on which Krugman is clearly right: it will hurt the economy, which now will be viewed as entirely Obama's fault; and rewarding blackmail like this is exceptionally dangerous. Sometimes you need to bite the bullet or it will only get worse (even leaving aside the clear alternatives to surrender or default that he ruled out from the start). That would take courage, however, a quality that (along with foresight) Obama appears entirely to lack.