I'm learning on the 152. Currently 27 hours into my PPL course at Denham.
I was originally going to learn on the PA-28 as there was some concern about the leg/knee/headroom for me in the 152 (it's a tightish fit) but those concerns were unfounded and I find it a super little aeroplane to fly.
I have flown 3-4 hours in a PA-28. Yes there's more room and it feels more stable than the 152 (especially on approach) but I like learning in an aeroplane which requires sensitive handling and rewards accurate flying. The 152 is excellent for Nav exercises too and it's also cheaper per hour at my training organisation (The Pilot Centre).
I intend to complete my PPL on the 152 and then convert to the PA-28 also when I want to carry more people around with me.
Hope this helps
Andy