We've been using VMWare here for years. I believe it's going on about 7 years or more since we started to use it.
Like so many tools that you have in your toolbox, once a person learns to use it a certain way, that person may not look to try using things in an alternative mode.
We upgraded to VMWare Workstation 8 some time ago - just when it hit the street. However, it wasn't until recently that I personally discovered Unity Mode. (Heck, for all I know, it was in VMWare prior to V8 and just never thought about it or tried it.)
I have to say, I use a lot of tools on a daily basis, but this one has to be one of the best. I have a quad-head monitor setup. One of the drawbacks to using VMWare was only having one monitor. Not any more. In Unity mode, I can run applications on the VM that simply display as another window on my primary desktop. This gives me the ability to run applications on my primary system and VMs and move them around within any of my 4 monitors as necessary. Over the past few weeks, in using this capability, my use of VMs has gone up. I no longer think of it as being a pain to use the VM instead of my desktop.
I don't know if there are any drawbacks to it. So far, nobody here that's tried this feature has had any issues with it or found any drawbacks.
I just wanted to share our experience in case this is something you have not had the chance to try yet.