Prolonged cardio takes too much time and ultimately slows your metabolism making it harder to lose weight.
Steady cardio is a muscle-wasting activity.
The repetitive nature of cardio invites injuries and impaired motor control.
You cannot out train (or out cardio for that matter) your eating habits. Change them, or else.
To avoid a plateau, your cardio needs to be more varied.
Continuous aerobic work plateaus after about 8 weeks.
The calories you burn during the workout don't matter than much and calorie burning stops shortly after the exercise is done.
There are some studies cited at the end of the article that highlight the ineffectiveness of traditional cardio. It is not just my opinion.