The guys at Flying Meat Software have released an update to their excellent, inexpensive image editor, Acorn, which is now up to version 3. One of the better reviews is here at Mac App Storm. Like many Mac apps these days, you can also get it via the Mac app store, allowing you to install it on all of your family computers.
While I personally won't be switching to it from Pixelmator, what I've said before holds true - they'r both excellent programs and it's more a matter of which suits your style. Check it out.
Note: Updated to dix a typo in mispelling "Mac"