Today’s possibly stretching-a-point Technology Analogy
In a previous article I compared the situation of Windows 8 on the desktop to that of OS/2 in the late 80s.
Windows Phone 8 is in a different position. While Windows 8 gets its awkwardness from the need to provide compatibility with the dominant platform—which in this case means earlier versions of Windows—the dominant platforms competing with Windows Phone are iOS and Android. And it’s totally incompatible with both.
So, why choose Windows Phone? Not because it has greater capabilities, all in all, than its competition. It doesn’t have any very significant platform-exclusive applications. It isn’t any more open (in either a useful or fun kind of way). There are two reasons you might choose it: a preference for its interaction design, or integration with some networked services.
BeOS is an operating system dating from the mid-90s developed, according to Wikipedia, “on the principles of clarity and a clean, uncluttered design”. (Sounds familiar?) It was pretty to look at and nice to use. It had decent networking support and made good use of the hardware available to it.
But it was always going to have niche appeal. By the time of its release, Windows 95 was dominant and generally tolerated by mass-market users, while Unix-based operating systems like Linux, FreeBSD, and NeXTSTEP were working their way down from higher-end workstations with hacker appeal. BeOS was incompatible, no cheaper, no more open, and ultimately more limited by lack of useful applications. It remains a likeable curio.
The Breakfast Post 
I should add: Someone will tell me off if I don’t mention that BeOS sort-of lives on in the form of Haiku (http://www.haiku-os.org/), an OS written from scratch by enthusiasts to resemble it.
Haiku has the advantage of being open source and therefore perhaps more fun, but the disadvantage of no longer being a particularly advanced OS. It’s still nice to look at though.
I actually bought a copy of BeOS, quite late on — in 1999 — though I don’t recall ever doing much with it. What I really wanted was the dedicated hardware the company initially sold, but I couldn’t afford that.