Oh... I use it for my gmail account. I get a TON of emails over the course of the day and I really like the way that Inbox groups them. Makes things so much easier to go through. And I really like Inbox's UX... I really find it speedy to just drag down to go up a level.
Every once and a while I got back to the Gmail app, but I really prefer Inbox, even with its limitations.
Now, I do use Gmail Web on my desktop... both happily co-exist. There I can go in and clean up old junk and some more complicated stuff... but its all Inbox on mobile.