It really enhance the sound of the instrument. It sounds more full. The point is that you heard the difference when you switch off this pedal. It won't make your bass sounds like a professionnal one.
I'm not keeping it and instead I'll change my pickups: better result for the same price. I can't tell how it enhance the sound of a really good pickup, maybe more than of a bad one.
For a solo, it's a good pedal to have because it raise a little the sound (even with the boost off) and make it a bit more clear. You'd better place it at the very start of your chain, just after the tuner.
Taurus Servo Enhancer