if you want in your face distortion, as in, really hardcore metal-like distortion, then the boss bass overdrive's for you.
however, i feel that the odb-3 is a tad too noisy when maxed out for the metal distortion, and for subtle distortions, it just sounds very plastic/fake (ok, i'm not too good at describing sounds) Just that something is done to the low end, kindof muddies it quite a bit
i reccomand an xotic bass bb preamp tho, if you;'re into light distortion. Minimal to almost no noise, very transparent, good stuff