Like everything else… it depends. You can argue it either way.
Most cardio really doesn’t burn that many calories and studies have shown that most people eat a little bit more when they do cardio and that “little bit more” is almost always exactly the same amount of calories that were burned in the cardio session. If you do cardio, you still have to be strict with your diet that you don’t unconsciously allow yourself those extra calories.
It’s also hard to tell how many calories you’re actually burning. Most of the machines that tell you how many calories you’ve burned are wrong. But let’s say that you work out for an hour 3x per week and that burns about 300 calories per session and about 900 calories per week. I think that’s about normal. IIRC, 1 pound of fat is 3500 calories. So, 3 hours and you’ve worked a little over a quarter of a pound of fat off. Over a month, that’s an extra pound of fat (assuming that you’re just losing fat, which is a bad assumption.)
To me that doesn’t seem like a lot of bang for your buck when you can get a similar effect by just not eating that 900 calories over the course of the week.
On the other hand, every little bit helps when you’re dieting. And you can always do more cardio and you can always do more intense cardio and get more weight loss. If you’ve got the time and losing weight is your goal, this can be another tool to help you get there.