By and large, happy. The experience of war over the past two generations had been: Men march off, spome peple do extremely heroic things, some die, which is sad in a heroic kind of way, and they come back next spring and we party. The expectation was that this would be repeated, only on a grander scale (and thus by extension with a bigger victory). War, to the popular culture of the time, was, if not an unalloyed good, then an overall positive thing. It allowed you to prove yourself, it made you better people, and of course, you would win. And it ended the interminable sense of crisis. All problems would be resolved now.
Even those people- and they were quite afew - who were unhappy about it did not consider war in general a horror as much as a deplorable necessity, a bad thing with good sides. Look at the reaction of the majority of the SPD - regret, patriotic resolve, and the general conviction that this would soon be over and then one could go back to business as usual, and have proven one's loyalty. Not everyone was in the streets partying, but most people were at least willing to take it in their stride and do their bit.