The 'Juice' preamp is able to handle a mix of both strong and weak signals. It's housing provides excellent shielding to prevent interfering signals from entering and behaving as a form of multipath interference. It provides an appropriate amount of gain for most residential applications and has very competitive noise/distortion specs relative to competing products.
Bear in mind... The primary purpose of a preamplifier is to overcome losses due to coax and splitting. No amplifier adds to the performance of an antenna. If you feed an amp with 'garbage' it will only push 'garbage' down the line. Just like a pump, if you put polluted water in, don't expect the output to be fit to drink.
Again, a preamp will not be of much use if neither of these conditions exist:
Splitting to multiple TVs
More than 50' of coax between the antenna and tuner