On my way down from 272lbs. I tried lots of different exercise routines, for like a year I held my diet guidelines steady and did one hour a day on an elliptical machine at a pretty good clip. The results were not stellar for me, I only dropped a couple of pounds for the year. I think what happens for a lot of people who do low impact, steady state cardio is that they end up adjusting their diet and eating more calories.
There was another time in my life when I had the ability to take massively long walks, where I would go on like 5-7 hour treks. I didn't do it to lose weight, but just because I had the time and I really loved doing it. When I did those walks I dropped fat really fast. Probably it was because I just spent so many hours moving. Very few people could do that regularly though.