Always have had connectivity issues with my devices. That being said, it could be Apple's problems with Bluetooth it seems with IOS 8. Now that I'm running IOS 9 and it won't even connect at all with the BACtrack. Hopefully both apple and BACTrack are working on a solution for iOS 9 Bluetooth woes. App and device work well when it connect. Seems very accurate. App is intuitive for the most part.
I used to own the S80 and was a strong believer that there could not be a better model, but after switching to the more compact Mobile I am very pleased with my choice. The zero tolerance projector is an awesome feature to determine when you should stop drinking prior to driving so that you can drive in confidence that you are aware of surroundings using all your senses. This is an amazing product!!!