I purchased the band last may and have to say, it’s excellent. I haven’t had any problems with the app and found the readings very accurate, I have had a very high reading for my heart on a few occasions and went to get it double checked at hospital. I can say with personal experience the reading on the app does go up to 150bpm but my readings have been 165bpm on a few occasions...all the individual sections off the app gives advice on your readings.
I originally set the band to take my reading every hour and recently noticed it’s also taking intermittent readings itself.