The title sums up these strings in one word - they're SMOOTH!
Smooth to the touch, smooth-sounding, smoothly *sliding* under your fingers, and producing the smoothest *blues* tone, just as their name promises!
I've never played a string that feels as comfortable to play, or that keeps it tonal character for as long. I tend to forget to change these for many months on end, because they just mellow out a bit with age, they never really "die". This long useful life makes the high price rather irrelevant IMO.
More importantly, I just *love* playing my guitar when it is stringed with a set of blues sliders! And so it always is.
CAVEAT: the dark "vintage" tone of these strings works much better for blues than for metal.