Yes, I’m one of those lucky S.O.B.s that was able to get through the massive waiting list for Mailbox. After using it for a few weeks or so, I can tell you, for what it’s worth, I love it.
If you haven’t used it, it goes a little something like this: the product team made a critical observation in how we all manage email: you receive it, you read it, you figure out if you need to do something about it, and you either do what needs to be done, you put it off to later, or you delete the email. It’s funny even writing about this as though this is a breakthrough–this is so friggin obvious–but email clients to date have done a terrible job of supporting this behavior.
To accommodate this triage process, the app overlays interactions generally associated with task list apps onto your email inbox. It accomplishes this by creating a few folders and labels in your Gmail account that are scripted to make the app’s hocus pocus possible. If you handle your email on your phone, you’ll never really notice this. If you check out your Gmail account in a browser you’ll probably see a label or folder here or there that makes it possible.
Starting out
I set up Mailbox with my personal email account. I’m still managing my work-related emails through Apple’s iOS Mail. I turned off push notifications for Mail and for the Gmail iPhone client, favoring Mailbox as the only push notif option.
The app is well-executed, with a great deal of attention paid to visual design details–the typography speaks to this with clear, understated styles. Most importantly, the interaction framework has been very well-executed, with clear states of use.
At first, I thought the gestural vocabulary of the app was a little odd, specifically the long-swipe gesture for deleting an email. Really? We’re going to intriduce a new type of swipe for something as basic as deleting an email? I kept accidentally archiving emails that were headed for the trash. But after a few days of use I became accustomed to this started swipe-sorting my emails with ease.
I started quick-swiping emails to the right–archive that stuff for a rainy day.
I started long-swiping emails to the right–trash, never to be seen again. OK, so far so good.

Awesome gif on Mailbox swipe interactions by matthewmooredesign.com.
The Breakthrough
Interesting things started to happen when I got the hang of swiping emails to the left and marking them to be read later. This feature on the app gives you the chance to not only designate an email for later but designate what “later” means for this specific email. Swipe an email to the left and you see this:

That email about that thing that I am going to deal with after work? Mark that for “this evening,” an option that resurfaces the email in my inbox at 6pm. SXSW badge pickup bar code email? Friday, 9pm, right after I touchdown in Austin. Evite to a 4yo birthday party that my kid is attending? 3/30, 8am, two hours before the party starts.
Damn… Email is where I want it when I want it, not just starred and sitting there. This was huge. The ambiguity of other tools (flags, stars) leave the actual productivity twisting in the wind.Mailbox wants to know not just what email is important but when it’s important. This simple grid of selections is like a gentle nudge from the the project manager of your life, asking “Sure thing, we can deal with that later. What time did you have in mind?”
At first, I thought this was just a nice thing to have, but it turns out that’s exactly what I needed in my inbox. I started to actually enjoy managing my email. The app gives me an actual sense of control over the torrent of email in my life. I was still skeptical that this would really change my behavior until something interesting and totally unexpected happened:
I became a total whore for Inbox Zero.

Damn straight.
The Verdict
I am now actively using my inbox in the way that I think it was originally intended: as both an email inbox and as a personal task list.
The app is not without its shortcomings. Among some other little things, there’s no support for drafts (yet). But this is coming in time, and I’m confident that this team will nail it.
I have to say, I’m impressed. Really impressed. The types of interactions they are dealing with here are repetitive actions that happen in the background of people’s lives. The margin for error is virtually nil. And with the hype around this app (especially among my beloved hyper-talented-hipster-designer friends) made me wonder if this was being overhyped. And at first, I sort of thought that it was but after working through a few cycles of my email I really came around. Kudos to the team!
Open The Window: In Praise of @Mailbox: Yes, I’m one of those lucky S.O.B.s that was able to get through the m… http://t.co/YxVAuCVXu6
Inbox Zero, Mailbox and a smarter way to handle email : http://t.co/8awcT6Qs0o #ux
@dpan @mailbox Awesome! Can’t wait for them to get acquired and EOL their product!