I have. I started using this app to help with post partum weight and to get back into shape. I have lost 5lbs this month with eating healthier and being more active throughout the day.
Patients is a big key with weight loss. Portion control too. Don't under eat though.
I've lost about 30 lbs, but it sure didn't happen overnight. And I was extremely discouraged at times (just look through old forums and you'll see that lol, I made several posts exactly like this one).
If you truly, truly feel like you're doing everything right and not seeing any results, it never hurts to check with a doctor. Just mention it at your next physical.
But yes, this app has helped me a lot, and others. But the app isn't a miracle pill. You've gotta be diligent and have a lot of self-discipline about eating right. How you eat is even more important for weight loss than exercise. And patience! Because if you get discouraged and give up then you're certainly not going to see any improvement.