Others have already described how good they sound. For me, one of the most useful features is the ability to switch between single coil and hambucker modes, as this has a great influence on the sound and being able to choose between two radically different kinds of pickups for different music styles is a huge advantage. As for the "voices", I don't really understand why they decided to offer this selectable voices feature instead of just adding the middle control to the EQ, that would have made it even more versatile IMO.
I think they just wanted to basically made it easy to commute between two main kind of sounds, that is a vintage sound and a modern active sound, but it's rare that you have to do this on the fly while you're in a concert (usually you don't touch the sound in the middle of a concert...), so I would have preferred a 3 band EQ.
However, this is going to be a great upgrade for several basses. It definitely was on mine.
The installation is not so easy: you have to be able to solder and, even in that case, it will probably take you several hours. Some wires needed to connect the boards are missing. Being an expensive and premium product, I don't think this is acceptable, considering how cheap it would have been to include 5/6 wires. You might also need several different tools in terms of screwdrivers, wrenches etc. If you realize you miss something, you might have to buy it, so don't start the work unless you know you can use another bass for some days.
If you've never done at least a simple pickup upgrade on a passive bass, starting with this could not be a good idea. You should also be ready to solve small compatibility issues. In my case, for example, the provided rubber was too high for my pickup cavities, I had to reuse the springs from the old pickups and paste them to the new pickups somehow.
If you have to pay a professional to install them, I guess it wouldn't be cheap as the installation takes time. Some basses from Cort or Spector already offer these pickups and going directly with one of these basses could be a better idea.
If you're used to working on your basses, then you may go for it.