Bottom line: Has some unique selling points
Review: myWriterTools promises a lot and, for the most part, it delivers. Like other editing software, myWriterTools finds wordy sentences, homophone errors, passive sentences, and many more common writing flaws. But myWriterTools has some major selling points that differentiate the product from other editing software.
For example, you can see and edit all myWriterTools' rules and word lists. This means you can customize the software to your specific needs, industry, and house-style. You can remove words you don't want corrected, add new substitutions, and add your own word lists.
This feature compensates for the relatively short lists of jargon, cliches, and homophones that come with myWriterTools. These lists are still useful; they are just not as comprehensive as, say, StyleWriter or Editor.
myWriterTools seems to find straight textual matches rather than patterns. This has the disadvantage of finding fewer potential errors but has the advantage of reducing the number of "false positives" (compare Grammar Expert Plus).
The part of myWriterTools we like the most is the "FormatFixer", which fixes common formatting problems. In our professional lives as editors of lawyers' writing, we often have to correct the same formatting problems. For example, in pinpoint page spans we must often change hyphens to en-dashes; and change hyphens in the body of a document to em-dashes. Now, we can use myWriterTools to make these changes automatically, at a click of a button.
Another common problem we encounter as editors of lawyers' writing is that lawyers pay little attention to whether punctuation comes inside or outside quotation marks. Often, our clients are inconsistent about such "trivial" matters. But, now, we can correct the problem in one go, by using myWriterTools' feature that places commas and periods inside quotes. (It would be nice to also have the reverse option, since some non-American style guides prefer punctuation outside quotes).
Other useful features include the ability to convert a document from US English to UK English and vice-versa and the ability to turn on Word's "track changes" so that you can see the changes myWriterTools makes and accept or reject them later.
myWriterTools, like all editing software, isn't perfect. For example, when we ran the software on our test document, the software flagged "disqualification" as a long word; but we wanted to keep the word "disqualification" since we were using it as a legal term of art ("constitutional disqualification"). Yet myWriterTools did not let us ignore "disqualification", which meant the software kept flagging every instance of the word. An "Ignore All" feature would have come in handy. When we tried searching for long sentences, we received a "Run-time" error and we couldn't start the software again without closing Word and re-opening it.
The software's makers are honest about myWriterTools' limitations and they are always working to improve the software. They also claim to have a fairly automated upgrade system where users can quite seamlessly get a new version. [UPDATE: just a few hours after alerting myWriterTools to our "Run-time" error, they had fixed the problem and had an updated version ready for everyone to download].
In any event, these kinds of technical glitches, which affect almost all the software we've tested, are relatively minor. myWriterTools is fundamentally a very helpful tool for writers, editors, and proofreaders. Much cheaper than its main competitors, the software is also excellent value.