I tried out the free online version and very soon subscribed to the premium edition, which, among other things, builds the proofing features right into the WordPress editor, so one doesn’t have to copy large chunks of text back and forth. An incredible boon for bloggers!
Either version does things like:
- checking grammar
- improving dull paragraph structure
- find repeated words and phrases
- checking consistency of spelling, hyphenation, and capitalization;
- identifying sticky sentences
- eliminating clichés and redundancies
The full analysis of a given text reveals innumerable unpleasantries, but working tediously through them does result in a significantly better-sounding text. Just don’t act on every point it criticises.