^ Wow. Are you sure? I'm in sequence 6 on my second playthrough and I've well exceeded 10 hours at least. Then again the sidequests add many hours to the clock. And developers always exaggerate when it comes to the length of their games.
Nevertheless, I'm pretty sure the campaign in this is still longer than in Declassified which I hear takes 2 hours at most to complete.
Probably took me 7-10 hours or so, but i did not really do any sidequests and only main missions, with a little running around killing here and there. I just wanted to beat it before the game save glitched which it still has not.
I have been hearing just horrible things about BLOPS single player on the Vita. I have heard you can beat it in an hour, how that is even possible for a game to be that short i have no idea.
^ I hear the levels in Vita's Black Ops are pretty much the size of an average house, and that there's like only ten of those levels. That most likely explains the length.
On topic, the story in this might actually be somewhat shorter than I expected. The later levels are really quickly over. Still, I'd say this game gives you many hours of gameplay if you're going to complete all of the sidequests and go for the trophies, some of which are tedious though.