I've been using my armband pretty consistently - and I feel like I am finally getting real results with it.
You can see here that even though I'm not hitting the calorie burn goal on average - I am however, keeping my calories even with it. When I check the progress throughout the day, I can see if I'm behind target, and adjust my calorie intake on a daily level.
This has been a tremendous help in finding out exactly how much to eat, rather than an estimate.
I've noticed that apps like Runkeeper give me an estimated burn calories of way higher than my Body Media armband does - and it can vary by quite a bit. To stay on the safe side, I stick to what the armband suggests rather than an estimate based on my BMI.
I also am glad to see that my daily average for exercise is 42 minutes a day - across a period of 7 days. I'm getting some form of exercise every single day - either running, or Crossfit - and that's important.