Federico tweeted that iOS mail clients are today what Twitter clients were a few years back. Sure, but I never cared so much about reading and writing tweets because my job(s) didn't depend on it. E-mail is mission critical.
I loved Mailbox but it never did Outlook. Acompli was a leap forward, flawlessly blending Outlook and Gmail; I even liked its built-in calendar and recent files feature. I thought it was good that Microsoft bought it - but then innovation stalled and they removed the one feature I was really enamored with - programmable long swipes. Yeah, this may have been a power user feature that confused newbies, but this power user was waiting for someone to re-implement this helpful feature.
Then came Airmail, the most customizable iOS mail client yet. Sure, the new app has a few rough edges, but I'm happy to struggle through a few rough edges, because it has long swipes! And, easy integration with organizational apps like Todoist (you can swipe to Todoist, which almost makes me look forward to emails).