Unity got good intergration with Expose, but according to Parallels team, it's simple to implement: just put the Windows' window into a Mac holder (a Mac window) and then voila, Expose just works. in my experience though, this feature is still a bit buggy, like redraw, for instance, sometimes takes 1 seconds to refresh, or windows still overlap etc.
Coherence is nice in the sense that it offers a lot of configurability features, so i can make the program behave the way i want. for example, i dont need Windows apps to show up in OSX dock, so i want to turn this off. under Unity, there's no way i can do this.
in RC1 release, i now can choose to have Windows taskbar visible (which is the reason i start thinking to switch) however, it doesn't always work in a dual/multiple monitor system. it lose mouse focus all the time. at first i thought it crashed but this happens more and more so i looked into it and found out that there's something to do with resolution, so there's a mis-alignment between where i think i click and where the VM instructs the mouse to click (VMware admit that they haven't solved this). this is very annoying sometimes.
last point, is running fusion/parallels on a laptop. there are quite many people having problems with their laptops not being able to sleep. although it is not clear as who or what causes it, but all those people including me use Parallels. Parallels team said that they were able to recreate the situation and concluded that it is because of a problem with RAM - but many people still got it even after they have changed RAM.
so for now while Fusion is still free and i already own PD, i'll just sit aside and watch, see what's happening when Fusion 1.0 is released. maybe it's not as good as it is promised, just like PD3.0
my 0.02
