I use Fusion in Unity mode on my main computer all the time. Outlook on Windows is my normal email client, and I do Windows development using Visual Studio, but most everything else I do on the Mac side.
After waiting until the official release and excitedly upgrading my VM from Windows 7 to 10 last night, I was saddened to discover that Unity was behaving very strangely - sometimes it would show the Windows desktop overlapping my Mac icons, sometimes it would display the taskbar sometimes not, sometimes nothing in Windows (even running Windows programs) would be visible. I did a bunch of Google searches and did not find anyone else complaining of this problem, so I was afraid it was only me! But I am relieved to find this post this morning - to see that it is a known issue for which a solution is being actively pursued by Vmware. I am a little disappointed that a solution wasn't found during the TP days to be ready for the actual release of Windows 10, but I understand that Unity is a complicated thing and it takes time. I just hope not too much more time.
For now, I think I'll just restore my Win7 VM backup, and eagerly await news of a fix.