First off I am comparing these strings to my experience with other brands when they were new, so its not just the 'new strings vs old dead ones.
For years I was using D'Addario for my bass (Fender '97 american precision deluxe) and swore by them. My bass was feeling like a bit of a plank with rubber bands on, so I splashed out on some of these and wow! Ok, granted I did the full bass adjustment when I changed strings, but my bass feels more electric and alive than it ever has. They feel more responsive and snappy than others have (even new) and the tone is just perfect. I was really unhappy with my bass while using other brands, but with these, it feels like I have a whole new and better bass.
I have now fallen back in love with my instrument!