Mac: Pixelmator, our pick for the best image editor on Mac, was updated today with a bunch of new Yosemite features alongside a redesigned interface.
The first thing you'll notice in the update is a redesign that brings it in line with Yosemite's flatter look and transparency. Beyond that, Pixelmator also gets support for iCloud Drive, Handoff support to work with the iPad app, and new Repair Tool Action Extensions. These extensions allow you to quickly edit images in apps that support it like Mail and TextEdit using Pixelmator. It's a little change, but if you edit photos in Mail a lot, it's useful.
Pixelmator ($37.99) [Mac App Store]