I have been using the star/archive/spam method for a long time now in regular gmail. The inbox interface seems to slow down my flow, as it has little inbetween steps I find irrelevant.

I zip through my email in gmail using keybindings, se/e/! respectively with gmail set to go to next message automatically. Takes me a few seconds to go through about 20 emails, then I circle back to the ones I starred.

Inbox looks better, but feels a bit worse for me. Also, the no apps support as always is a downer, but us apps users are used to it.