Is a 14-inch folding e-bike good for commuting?

For short trips and mixed commutes, yes. It folds small enough to take indoors or onto transit. For long distances or hilly routes, a larger-wheel e-bike with gears is more comfortable.

Only gently. The single speed gives you no gear range, so the motor does most of the work and steep climbs will be a strain. Flat city routes suit it best.

How does it compare with a 20-inch folding e-bike?

The 14-inch model folds smaller and is easier to store, but the 20-inch version rides more stably and rolls over rough pavement better. Choose 14 inches for portability, 20 for comfort.

Is the steel frame a problem?

Steel is strong and inexpensive but heavier than aluminum. That matters when you carry the folded bike up stairs or lift it into a car.

What should I check before riding?

Check the frame hinge and latch are locked, tires are at pressure, and the brakes stop the bike firmly. Small wheels need more attention to tire pressure than large ones.