When it comes to bugs and crashes, I'm fairly confident that the team will fix them. Maybe not every single one but given the rate of progress I'm assuming they're throwing a fair chuck of resources at Unity and bugs will get squashed sooner than later.

But....

It's not the bugs I'm worried about. The genuine usability issues are where there could be trouble. If they're not prepared to be flexible and take onboard the findings of end users then they might wind up with an enormously reliable, stable and dependable desktop that's a pain in the arse to use. From what I've seen in the past Canonical are generally receptive to their users although the buttons on the left of title bars issue without an easily accessible option somewhere suggests this doesn't hold true in absolutely every case. But hey, no ones perfect.

I'm finding Unity is generally sound but there's usability issues specific to a triple head system that will need addressing at some stage in my opinion. They'd also be relevant in a twin head system as well.

Strangely I'd say initially the most alien aspect for me was how the global menu system works. As an Amiga user, my first proper exposure to a real GUI based machine had a very similar system. With multiple apps open when you needed to access an apps menu you'd first need to have one of the apps windows selected, and then hit the right menu button and to the top of the screen you go. I worked full-time for years with Amiga's, and this was programmed into muscle memory for me, but after many, many more years on the wrong end of Windows based machines I've become accustomed to the way things are with menus in the window, not the top of the screen. There's much deja view in this particular aspect of Unity and I'm getting used to it again, but it has taken the best part of a week for it to start to become second nature.