You know the old William Gibson line that cyberspace is the place where telephone conversations happen? Not in the hardware at either end, but in the "space between"? Computing has moved there too.
Work used to happen on a device and then was transferred to other devices, either manually (floppies, email) or later automatically (sync, dropbox). Thanks to the web, mobile devices and lots of data, that's changed: Google Apps led the way, but Evernote etc all let you do your work in the space between devices.
Nowadays, putting the device first over the data (or ignoring other devices entirely, like this app does) is like putting the phone first over the call: beautiful, elegant hardware, refined way to dial, custom typeface for the numbers ... but you can't call anyone with it.
Apple in particular makes this mistake repeatedly. Photostream is device-first, so you have to work out what the hell is where and work out what you want to download to which machine. iTunes Match is device-first, so you're forever downloading and deleting tracks to make space on a particular device. Me.com tries to keep the sync truth on one of your devices, so conflicts abound. Notifications appear on all devices and often have to be dismissed individually on each of them. They see the world through the device first.
I suppose it's obvious why it happens -- they're a hardware company, and they grew up in a pre-networked world -- but I think misunderstanding this is one key reason they're seen as "bad at services" in comparison to Google, which is instinctively and entirely in "the space between devices".
As for this app, why would I ever want to be trapped in a single place again? They might as well have made it for an SE/30.