I never got beos and I don't really get haiku. Its a brilliantly designed multi tasking multimedia os. The underlying architecture is awesome. It is incredible effecient and beautiful underneath... But its the top layer that always got me.
It works incredibly well but the user interface is so horribly ugly and disgustingly bad for the eyes.
They need to make it skinnable or something, because out of the box all you can change is the wallpaper but the window borders and rest of it is just disgusting.
Yes I care about function, but the user interface needs to be somewhat elegant because you don't see whats under the hood, you see the car. Somehow, they always forgot that or ignored that.
BEOS failed because it worked great but looked like ****, regardless of what anyone else said. EVERYONE tried personal edition beos back in the day, but it was so ugly and uncustomizable no one except real nerds who really really care about what is under the hood could stand using it.
If you took the same underlying internals and made a pretty amiga like graphical ui on top I think it would have been a huge success. Eye candy does matter... No really, it does.
If someone takes haiku and makes everything the user sees be able to be changed to suit the users tastes... like linux, then it would have a real shot at getting some users. Until then its a great kernel with a really ****ty and ugly gui. But thats just my view.