From Pixelmator Team:
Pixelmator Pro is an incredibly powerful, beautiful, and easy to use image editor designed exclusively for Mac. With a wide range of professional-grade, nondestructive image editing tools, Pixelmator Pro lets you bring out the best in your photos, create gorgeous compositions and designs, draw, paint, apply stunning effects, design beautiful text, and edit images in just about any way you can imagine. And thanks to its intuitive and accessible design, Pixelmator Pro is delightfully easy to use -- whether you're just starting out with image editing or you're a seasoned pro.
The speed of the painting tools has been improved -- your first brushstroke should now be much faster.
You can now import brushes from the original Pixelmator.
When you drag and drop a layer to add it your image, it will now be added above your selected layer and not at the top of the layer stack.
You can now export images to JPEG-2000 format.
Fixed a number of cases that would make Pixelmator Pro stop responding when using the painting tools.
You can now use the Command-J and Command-Shift-J keyboard shortcuts to copy/cut and paste selections as layers.
Graphical artifacts would sometimes appear after repairing with the Repair tool. Fixed.
When reverting to an earlier version of your image, the background color would sometimes be incorrect. Fixed.
The colors of images exported to PSD would be incorrect when opened in Final Cut Pro X. Fixed.