I pretty much like all things Google, but Inbox just isn't for me. I much prefer good old fashioned Gmail on my iPhone. The way Inbox sorts my emails doesn't always make sense to me, and I suppose I'd rather sort it myself. There are definitely better email apps out there. I know because I've tried a bunch of them.
I like & hate inbox for the same features.
It´s the first time my Mailbox feels sorted and clean. That said Inbox dicards eamils as unimportant, doesn't show notifications for all emails and shows how much it knows about my friends, travel agrangements and so on.
I do think a manual hosted version would be really great but I doubt we will see something soon.
In the end its a Google Product which means no updates and in 2 years we get the next version of it. It lacks a lot of things you can't do with it. For instance multiple Accounts, S/MIME encryption and ways to highlight a lot more.