I had the Ultra Blacks on my ply bass for quite a long time: a year-and-a-half maybe. This was back before the GHS takeover. I had nothing like the experience that @PBandJazzBass describes up above. They were very nice under the hands, stiffer than the Super Silvers (which in turn are stiffer than the Silver Slaps), but not nearly as stiff as the Mittel Spirocores which followed them. The pitch wasn't as definite as with Spirocores or other metal strings, but to my ears not much worse than, say, with Obligatos. The timbre was warm and a bit gut-like, but certainly not as much as is delivered by the Super Silvers—which just came off my main, hybrid bass. There was a trade-off between (i) focus/definition of pitch and (ii) gut-like character in going between the Ultra Blacks and the Super Silvers. I would note that the E string in the Ultra Blacks set was very usable; however, the E in the Super Silvers was (to my ears anyway) unusable and I used a stark Spirocore E with the A, D, and G from the Super Silvers set. I agree that you need some patience to let the polymer in any of the Innovation strings align under tension and for the character and focus of the strings to develop. A couple of weeks does it.