One consideration: the Martian atmospheric pressure is less than 1% of Earth's, meaning people will have to wear pressure suits to avoid depressurization and radiation (also due to lack of magnetic field). This would increase the net weight and resistance of all movements when not in a base. Also, I've heard that bases might need to be underground to reduce radiation exposure. Closer to the center of the planet = stronger gravitational effect. I doubt either of these would make up for the huge difference in gravity, but they might have some effect.
Regarding populating Mars, the low gravity would probably have a weird effect on fetuses' development. I saw something once about how zero gravity would not allow a fetus to develop at all, so 1/3 G would probably at the least cause severe birth defects.