Haiku is very pleasing in an eyecandy sort of way, but that's sadly all it has going for it.

I personally wouldn't use it as a serious OS.

I think Haiku is in that "last 5%" phase. They have something that is 95% of the way there, it's 95% cool, but frustratingly, that last 5% is really important; there's a lot of boring, thankless work with any software that has broad reach.

Most people don't like doing it, but in order for the operating system to be "good", you really need most of this unsexy stuff to work; you need to be able to easily install WiFi drivers, you need to support most modern video cards, you need to suss out the minutia of the graphics APIs, you need to test every possible edge case in the filesystem, you need to ensure that file associations are consistent, etc.

I've mentioned this before, but this is part of what I respect so much about the Wine project. It's been going on for decades, each release gets a little better, and a lot of that work is almost certainly the thankless boring stuff that is absolutely necessary to get Wine to be "production ready".

I ran Haiku a bit on an old laptop, and I do actually like it. It's ridiculously fast and snappy (even beating Linux in some cases), and I really do wish them the best, but as of right now I don't think it's viable quite yet. I'm not 100% sure how they're going to tackle GPU drivers (since GPU drivers are almost an entire OS in their own right), but I would love to have something FOSS that takes us out of the codified mediocrity of POSIX.