I use a combination of Gmail on the desktop and Inbox on a phone. I tried to use Inbox on desktop for a while, but ended up switching back as the desktop version of Inbox was too dumbed down and controlling for my liking:

- The mobile app arbitrarily doesn't allow labelling something and keeping it in the inbox.

- It puts emails in the inbox under a folder when labelled by a filter, which usually ends obscuring important messages.

- It doesn't have something equivalent to inbox sections (I use the crap out of these as my inbox has multiple different streams of things to action in it from multiple email aliases - personal, business, opensource, travel, bills, etc).

- As others have mentioned, Inbox is not very information dense.

Google sure had a challenge updating Gmail, since there's so many people using it in different ways. It'd be really interesting to see their top usage patterns summarised.