I recently went the other way from 152/172 to a PA28-181.
Differences:
The two doors below the wing is much easier when you keep forgetting stuff in the flight bag for the walk around.
You will dent your head on a 152's wing, and the flaps on a 172.
Inspection of gear, fuel, brakes and wing is much easier on the Cessna.
The 152/172 landing gear is not directly connected to the rudder. It's via a bungee/spring system. I find I use a lot more differential brakes on the Cessnas.
The stall warning is mechanical in the Cessna.
No static-drain port on the Cessna. No alt-static at all in the 152.
Electric flaps are nice (Doesn't look like a ruddy great hand-brake to passengers), but don't give you the same control-feel as in the Piper.
The 152's fuel switch is either on or off. 1 less thing to worry about.
In flying, the 152 is lighter, less wing loading. It's less stable, but more nimble. I find it more fun, but probably not the passengers.
The 152, loaded in utility category, is spin approved. Have fun.
(If you know what you're doing, legal requirements, etc. etc.)
The tube-steel gears on the Cessnas will result in bounces rather than thumps if you land it a little hard. The Piper makes a crap pilot like me seem like a genius at landing. I'll still bounce the Cessnas on occasion, but my only "thump" landing in the Piper was the first one. All of the rest have been "greasers" and I don't know why. (well, I do, some low wing, ground effect, etc. etc., but I never really "felt" the difference. I just flew them.)
All of that having been said:
FLY THE AIRPLANE. All of these differences are minor, and the airplane tells you what it wants from you. I've flown the a few Cessna types, this Piper, and a few tail draggers and in the end, they're all airplanes and the fly very similarly. Switching between types is a great way to learn to feel the airplane.