I though Hangover 2 was brilliant, laugh out loud, roll around on the ground funny. I was laughing so hard my sides hurt afterwards.
The first one I thought, meh, it was ok. It was funny in parts, laughed more than your average comedy. But not nearly as funny as it was hyped to be.
IMO, the second one is on par with Superbad, 40 year old virgin, Wedding Crashers, Anchorman, Talladega Nights, and Bad Santa as my personal favorite comedies of the past decade. So if the trend continues, each film getting funnier, I say bring it on.