I really want to love Unibox. I used it full-time for a week or so. But I just seriously cannot get over the way it deals (or rather, doesn't deal) with folders and labels. If I put something in a folder or archive it, it disappears from the people-centric UI, and there's not an easy way to drilldown through folders. Also, things like group messages are super awkward with the people-centric thing.
If you like the interface and concept, I would definitely recommend Unibox over Mail Pilot- it's more polished in general. But it's a very opinionated mail client and I really couldn't get over its opinions.
Yeah I never use folders (or labels) — I am just not organised enough to actually use them. I tried for years. So Unibox really meshes with the way I deal with email.
If you like the interface and concept, I would definitely recommend Unibox over Mail Pilot- it's more polished in general. But it's a very opinionated mail client and I really couldn't get over its opinions.