My opinion only,
This is a hell of a good deal if you don't already have it.
The individual samples are a bit under the wire frequency spectrum-wise if you compare to some of the Kontakt and third party libraries.
The interface is way like the SampleLord sampler. Clean, efficient, simple. What is missing in Sonar via stacking synths is easily done in Sampletank by layering several samples, setting the volume and pan appropriate.
Can use SampleTank alone as one vsti instance and rival anything from any thousand dollar library with thoughtful programming..
Old technology, but it is really that good if you dive into it.
John