The biggest selling point for the new version: an improved WYSIWYG interface for post composition. You now have the option to compose posts in either Rich Text or HTML format, and as you type, a separate preview pane pops up and lets you see how your post is going to look. It would be nice if you could edit in the preview pane—for example, in one test post, a subject-verb disagreement eluded me in the composition window but popped into plain relief in the preview window, and it would have been easier to correct it the minute I saw it—but this feature is not a vital must-have.
Almost every word I publish on ForkBombr goes through MarsEdit.