Velvia Vision is essintially a plug-in interface for saturation using the Channel Mixer
(CM) along with some contrast adjutments.
In short, it's far better than the saturation slider in ACR or in Hue/Saturation (H/U) producing results with less noise.
There is little difference between the CM and H/S with amounts below about 25% but above that the CM wins out. Although, it is more clumbsy to implement without the help of actions.
Having everything wrapped up in a plugin may be worth the $25 price due to the convenience factor.