30 minutes in the cct should do it. Any more than that and I would suspect they are taking the p*** out of your wallet. It's going to be lighter on the controls (before the Pitts guys chip in I obviously mean relatively speaking) but not that much so. The xwind limits are less, 12kts for the 152 although it will do more. It's a little twitchier to keep straight on the deck in a gusty xwind. All of the stuff really you would expect from a lighter a/c.
Other than that there's not much difference at all. I jump from one to the other and can't say I really notice.