i like comparing reactos to chemistry:
lets say windows is a really complicated molecule that can cure cancer (lets face it though, windows is in actuality a cancer) that uses hundreds of atoms. reactos wants to be like windows, but it has no idea what compounds are used, so they make it up.
reactos just happens to use some, but not all, of the same molecular structure as windows, so instead of curing cancer, it just slows down the growth. as the molecule gets built upon, it gets closer and closer to reversing cancer, but the chances of this molecule ever becoming exactly like windows is very slim. they could both have the same amount of atoms, but 1 uses carbon while the other uses silicon. this 1 atom difference could mean that one is actually more efficient than the other, but it could also be the difference between functional and not.
i believe reactos needs to take everything 1 step at a time. cover stuff like drivers and kernel functionality first, then get to working with applications. they could probably rely on the wine project to do most of the work for them. once reactos' driver "molecule" becomes identical (or close to it) to windows', that should mean any driver you install will work without failure. an open source OS having the ability to install ANY windows driver is a powerful thing.
In any event, ReactOS poses some real value: it allows a user's software (whether proprietary or not) to be Freed from an OS that may be problematic in the future. e.g., Windows XP lifetime is about up and will no longer receive security updates, yet some Windows XP software does not run on Windows Vista or later. Likewise, some of this software may be dependent on hardware that has XP drivers but not Linux drivers.
There's value in all software being Free. Maybe not always on the date of release, or not even until a decade or more has passed, but at some point that old software is no longer supported, maintained, or sold by its original publisher, and Free versions allow continued maintenance and study long past those "artificial" deadlines.
Indeed. ReactOS is essentially the FreeDOS equivalent of early Windows implementations.
In Windows there's core functionnality and there's fluffy eye candy. Once it get sufficient to most people needs, the user base will increase, bringing awareness to the project, thus more developpers and resources. Recreating an OS from scratch is far from easy, and these guys have all my respect for doing this.