This app is great - I'm pretty bummed to just have found out about it now, while they're in the process of turning off the service in June 2018. Hope there's another app i can find that works similarly... AirTable is great, but I can't use it for a full database for certain projects because of their freemium account limits.
Fieldbook is obscure enough that it offers more privacy than Google Sheets (data directly linked to your Google profile, directly searchable by CIA/NSA, etc). Unfortunately Fieldbook is also Silicon Valley, ex-Googlers and ex-Grouponers so I wouldn't keep anything too private there. US privacy issues limit its usefulness.
Not only is the app brilliant, the company itself is simply amazing. Very responsive and customer oriented.