Tom’s Hardware just published a very long 11-pages review of Win4Lin Pro Desktop providing this conclusion:
Whether Win4Lin can completely replace a native Windows installation remains to be seen. For low-intensity exercises like Microsoft Office interaction it does pretty well, but propagation delays owing to operating Windows within Linux may be problematic for professional graphics designers.
This does not mean Win4Lin is unsuitable for ordinary usage requirements, however. But considering that gaming functionality differs vastly from the majority of desktop applications, which explains the specialized capability of TransGaming’s Cedega framework, Win4Lin does a fine job of meeting its target objective. Ostensibly, this is to enable Windows applications to operate while Linux is live, and Win4Lin delivers exactly that for many productivity and content creation suites.
Read the whole review at source.
Note that reviewers conclusion, inability to run intensive graphic applications, is a current limit of all kind of virtualization products, included ones from market leader VMware.
So I won’t put the focus on this aspect but on the comparison between any commercial grade product, Win4Lin Pro included, and the high quality, free VMware Player, which substantially changed the way vendors have to present themselves to the market.