FUD, Unity is great and you know it. People bashing Unity have not really tried it yet.
It has a very opinionated approach to things and throws away a lot of customisation options (focus follows mouse, you can't move the launcher or go back to a standard taskbar etc).
I need for example right-click menues sometimes and those are simply not supported. So the only workaround is installing packages that get me applications menues back which is then a mess where the buttons to close a window switch from left to right depending on fullscreen or windows all the time. Not that I liked top-menues to start with anyway. And certainly lot's of applications just work badly with the top-menu simply because Linux-apps never were written for that. So you get stuff like double-menues even with some applications which are in the offical distro.
Or the idea to use F10 as a system key - sorry, but it just isn't one and never was. Which is why it's used by lots of applications which suddenly miss a key now - who came up with this shit?
There is one reason Ubuntu stays on my Laptop - it works most of the time good enough with the hardware. And I can live with Unity most of the time. But Unity is the reason why Ubuntu doesn't make it on my desktop.
After 3 days I just installed Awesome and went from there. Unity provides me absolutely nothing that I want that Awesome doesn't. The only thing it does for me is get in the way.
Give me a break.
Whoever thought that was a good idea needs to be thrown off the team, forever. It drove me absolutely nuts until I finally managed to get rid of it.
I use FVWM2 at work with two monitors, when I have time I plan on moving to xmonad. I've used Dropbox and a few other lightweight WMs too. They all worked OK with my dual-monitor setup.
I've used Unity at home since the beginning, and it's the single worst multi-screen experience I've ever had. I only stick with it in hopes that I'll get to watch it evolve into something useable.