Ideally, when you press the brake pedal, it should feel hard as a rock. There can be a tiny bit of dead space at the top of the pedal travel, but as soon as the brakes start grabbing, the pedal shouldn't give. Pushing harder should make you stop faster, but it shouldn't make the pedal move. That way, you can control your braking with pedal pressure, not pedal travel. It's more intuitive and confidence-inspiring, and gives the best feedback.
Cars are rarely engineered that way, unfortunately. There's always a little bit of "give" in the pedal. Some vehicles have more than others. But the pedal should still be firm when the brakes are engaged, and you should still be controlling your brakes mainly with pedal pressure, not pedal travel.
If it's not like that, it's spongy.
And if pressing harder makes the pedal move but doesn't make the vehicle decelerate any faster, that's even worse. It's the opposite of how the pedal should work.