The big issue with H2 is storage. If you store it as compressed gas, your max range will be about the length of a long runway. Liquify it, and for a practical range you'll fill the whole fuselage with a tank and insulation. Metal hydride storage is denser, but you need to heat it to release the gas. Someone may overcome these issues someday, but it doesn't look promising right now.
Yes, the C152 has been around, but it's descended from the 1946 C140 which was a better, more efficient airplane. There was even a flapless C120 which was useful for building proficiency in slips!
