Robert Samuelson sez the budget deal was a victory for liberals:

But the budget deal does reflect national priorities, for good or ill. It's mostly a triumph of the welfare state over the Pentagon. Even before the deal, the Obama administration projected that -- assuming continued withdrawals from Iraq and Afghanistan -- defense spending would shrink to 15 percent of the budget by 2016. This would be the lowest share since before World War II. The deal's added cuts, potentially as much as $950 billion over a decade, would reduce that further. In the 1950s and '60s, defense often was half of the budget.

Read it all. Sounds about right.

More:

Although Obama said he was willing to trim "entitlements" -- presumably, Social Security and Medicare -- he never laid out specific proposals or sought public support for them. There was more talk than action. Even if Obama had been more aggressive, he probably wouldn't have carried most liberals, who adamantly oppose cuts. They regard Social Security and Medicare as sacrosanct. Not a penny is to be trimmed from benefits.

This is an extreme, even fanatical stance. Social Security and Medicare do create a safety net for many millions of poor and near-poor retirees. But for millions of wealthier retirees, they are handouts. Liberals' unwillingness to admit and act on this distinction has long stifled meaningful budget debate. This would have doomed a bigger agreement.