| Actually I've owned quite a few Fuzz Faces, and while some are better on the low end than others, most of the ones I've had are very usable.
One thing is I urge you not to buy the Dunlop red Fuzz Face. It doesn't sound terrible on guitar, but I remember that particular model not being friendly with the low end. The blue Jimi Hendrix one is fine though, I've got one of those. But the MXR Classic 108 Fuzz (which is the blue Jimi Hendrix Fuzz Face in a smaller enclosure) is cheaper, easier to fit on a pedalboard, easier to power, and it comes with the buffer switch that is handy for getting some funky Larry Graham style fuzztones.
And as far as options go, the tonal options of the Fuzz Face are not available via the Fuzz knob as you'd expect of any other pedal (unless you've got the buffer on on the Classic 108 Fuzz), but you can get a whole array of tones with your volume knob on your bass. That is if you're going for an aggressive tone, there are a lot of more muted and subdued fuzz tones available with just the fuzz knob of the Fuzz Face. But for the aggressive tones you'll want to use your bass' volume knob, and with my P bass the Fuzz Faces I've got will clean up all the way very easily with a little rolling of the volume knob, and get you any amount of dirt in between clean and rage.
Other than that the Fuzz Face is very touch responsive, so I wouldn't recommend it if you're a weak player if you want raging dirt, it rather requires an aggressive touch. But make no mistake about it, Fuzz Faces can rage pretty hard. Big Muff variants are much preferred on bass by many, and would be better for a weak touch. But everyone and their brother uses a Big Muff on bass, so the Fuzz Face is a good option if you don't want to sound like everybody else or prefer not to sound over-saturated. | 
