I’m hesitant, too, about plug-ins to Word. I’m a tech writer and used to use the old RoboHelp that was an add-on to Word (now it’s called RoboHelp for Word) and it worked okay, but there was always the underlying problem of synching to the release of Word that you had.
At one point, we wanted a new version of RH because it fixed some bugs that were extremely important to us, but to use that version, we needed to upgrade Word. When you consider the cost of upgrading Word, any add-in becomes an expensive product.
Consider this, too: if you are allowed to do personal work on a machine at the office, I think the IT department might be happier if you didn’t install an add-on to Word. (They still might have a problem with you installing software from an unknown company, but often will allow it if they have good anti-virus protection.)
I feel for the developer. He probably just started out doing it because he wanted something on Windows and then people heard about it and started asking for a copy. I think it’s good that he openly acknowledges Scrivener, and could even be a method of “payback” (by advertising for Scrivener).
The three-pane arrangement with the pods (or HUDs) is becoming more common in software in general – I see it in Adobe Framemaker and RoboHelp and in Microsoft Word (if you use View > Navigation Pane, or View > Document Map, and then expand Styles on the right) – so we can’t really consider that a rip-off.
I’m not a lawyer, but I think that A) you can’t copyright an idea and B) you have to prove that the rip-off resulted in you losing money. Also, as someone said, Microsoft does this all the time. My husband worked for a small start-up that made a product whose features eventually ended up in a Microsoft product, coincidentally not that long after some Microsoft guys stopped by the booth at a trade show…
I think Scrivener is great, and I love the fact that I don’t need a machine with the horsepower to handle Word to use it. I’m for Scrivener.