As Peter Cohen put it, Pixelmator is to Photoshop as Sketch 3 is to Adobe Illustrator and I couldn't agree more.
I don't use the most advanced Photoshop features and Pixelmator ($29.99 in the Mac App Store) has served me well as more than a very capable alternative to Adobe's image editing application. I use Pixelmator on a daily basis to edit press photographs, optimize images for web distribution, touch up snaps taken on my iPhone, create various compositions, convert between different formats and what not.
After issuing a major 3.1 update back in January with Mac Pro GPU acceleration and other goodies, the team is now teasing another forthcoming update, this one code-named Sandstone...