I own a 150D, as for learning they are a bit too simple and forgiving. The nice thing about a 150D is that it has a good payload compared to other versions. ( Cessna increased MTOW by 100 lbs when they added the rear windows but it did cost like 50 lbs).
Not so good is the old panel layout and some spare parts are a bit hard to get. The D and E are the weird models in the 150 range.
All things considered I'm happy with it.
-Kees