These strings have two main advantages: Tone and longevity, which in my opinion make them very similar to some Snake Oil strings I used to have a couple of years ago.
They stay fresh longer than most other strings to the degree that I leave them on the guitar up to several times longer. Both the tone and the tactile feeling stay pretty much the same for up to a few months, even with daily usage.
When they are new, they add some sort of roundness to the tone (I have used them on a Les Paul). This is NOT the same as the dull, lifeless tone regular strings develop when get old, greasy and oxidized, but more of a vintage-like tone, preserving top-end sparkle.
The price of these strings is actually surprisingly low when compared to regular strings, considering their long life.