Web app in a native app frame
Polarr is likely the best online photo editor out there. The fact it uses Web technology makes it work the same across all platforms. However, when I paid $9.90 for this program to download it from the App Store, I expected an actual, native Mac application. The expectation for a Mac program is that it uses native Mac OS application libraries and Mac OS user interface elements. Polarr for Mac uses Webkit for the entire window, there are no Mac OS elements. There is one major difference though: with the paid version you get RAW editing, which is more expensive to upgrade through the Chrome web store.
Core_ about Polarr Photo Editor Pro