I gave the mac version a try and tried to use it for weeks. It's not good. The app is slow on OSX, the team doesn't really respond to queries on Twitter, and you can't access your mail without an internet connection.
By far, in my opinion, the best iOs email client is CloudMagic. I've tried most of them and they nearly all suck, but I've been enjoying CloudMagic for a while now.
Yeah, it just came out so we're still fleshing out the page. The main http://inky.com page and the App Store description / screenshots (http://appstore.com/inkymail) give a more complete picture.
They nailed the one feature most "new" email clients fail at... IMAP. Unfortunately your accounts are accessible to the Inky developers due to "cloud sync."
IMAP is definitely a complex beast, and we're excited to offer this over many of our competitors. We believe all email users deserve a modern client with innovative features.