They're full, bright without shrillness, round without mud, they fit well in a mix and they even growl when needed. I've used them with flats and rounds, they sound great. I disliked my Jazz bass until I got these... Now I play it all the time. These pickups are definitely recommended.
I put a pair into my 2000 Fender US made Jazz. It has an Ash body maple board and it gave it a nice warm punchy tone. The output is low so I run mine through an Aguilar Tonehammer DI. You can just turn up the gain on your amp. True to Bartolini fashion (I play them in most of my basses), they have a warm low mid focus and has a nice bloom. They don't have that sizzle but for a passive pickup and a single passive control knob I'm not looking for that modern sound. Great pickups.
Replaced the jazz bass pickups in my Ibanez with these pups and turned it into an amazing sounding bass. Running these through a distortion or fuzz pedal is amazing.