I’ve had this for a few days. I find the app really intuitive to use and the historical data is super interesting.There is one glaring flaw. It can be avoided, thankfully, but it has left an extremely sour taste in my mouth.Let me explain. An Airthings device must be registered to an account. Great. But it was not clear to me that it can be registered to one account and one account only. I had the bright idea to have everyone in my family make their own Airthings account and connect to the device so they could all see the readings.When the first family member connected to the device, suddenly it was de-registered from my account. Whoops. There was no warning that connecting the device to another account would de-register it from its current account, or that doing so would COMPLETELY WIPE ALL HISTORICAL DATA and send the device into a 7 day calibration process all over again. There was certainly no prompt on my phone asking me for permission to transfer the device to the other account. My family member literally just clicked a button and bam, the device was registered and I was booted off.Slightly panicked, I had the family member de-register the device from their account and reclaimed the device on my own account. I hoped that the historical data would repopulate.It did not. Thankfully I only had the device for a few days, but can you image the pain of losing all the historical data if I told someone to make their own account to connect later on, like a year from now? It would have been horrible!As a bare minimum, Airthings should change their app to have a warning whenever all historical data will be deleted. And to ask the account that currently owns the device to approve changing the device owner to a new account! Because anyone could technically hijack the device at any time and wipe all the historical data! I have no idea why anyone would do so, but it would suck! And I hate not being in control of something like that.As long as you don’t try to register more than one account like I did, and you don’t have randos who might try to connect to the device without asking for permission, you should be fine.My annoyance over this makes me want to leave 1*, but literally everything else about the product is 5*, so I’ll settle for 4*. Hopefully the issue is fixed or at least addressed in a software update.