The 1975 C-150M, which model continued in 1976, and 1977 for a few aircraft, are virtually identical to the 152 firewall aft. As noted, the differences between a late 150, and 152, other than engine installation, are the flap travel limits, and 24 volt electrical system, and 70 pounds more gross weight. The cockpit arrangement, dimensions, and controls of a 1977 150M, and a 1977 152 are identical (other than flap selector, and engine instruments) if I recall correctly. The 150 with the 100HP O-200 is offered with either a 48", 50" or 52" pitch propeller, I have flown all three, and very much prefer the 48" pitch version (prop can be later changed, or re pitched). I am not aware that the 152 offered alternative pitches.
I did my first solo, on the first 152 which came into Canada, in 1977. Though everyone was eager to fly the 152, my preferences soon returned for the 150. My like for the 40 flaps was the major reason, though the really poor soft field performance rated high on my dislike list too. The prop on the basic 152 is not optimized for soft field flying, and produced very disappointing results in grass strips I used to happily frequent in 150's. Bear in mind that a major factor of the choice of the Lycoming 235 to replace the Continental O-200 was not dis-satisfaction with the O-200, but the fact that it was very unhappy running on 100LL. It still is. The Lycoming runs just fine on it.
A very good book has been written on the 150/152, by Clark, and is published by TAB. It explains all these differences well. My personal preference is the 150M over the 152, and that is based on lots of flying of both. I do not believe that either is more troublesome, or costly to operate than the other, if equally well cared for.
People say bad things about the 150M balked landing climb with full flaps extended. To those negative remarks I say: Not true, it is acceptable, safe, and design compliant!
To support my assertion, I offer the following video clips:
Aircraft :: C 150 40 flap ice takeoff video by PilotDAR - Photobucket
and...
Aircraft :: C150 40 Flap Takeoff video by PilotDAR - Photobucket
A full flap takeoff serves nearly no useful purpose, other than to confirm that a balked landing climb is possible. Do not attempt - not an approved technique!