The app itself is good but at times I start the timer and when I go back to stop it 70% of the time the timer has shut off.... It is so annoying because it defeats the purpose of the entire thing. I emailed the app so that they can fix this problem and never got a response. The positives are that it is visually easy to use and I love the graphs, but what good do they serve when they cannot be accurate since the timers shut off all of the time