They are the most recognised pedal brand, and for a while, their only 'bass overdrive' pedal was a nasty (in a good way) distortion pedal. So new bassists bought ODB3s in their droves looking for mild 'overdrive' only to be disappointed, then start researching their options to upgrade from their Boss pedal. So a lot of bassists now have a built-in dislike for Boss pedals. They've come out with the BB1-X now, but it's a bit crap, I sold mine after playing with it for only 5 minutes. Still have my ODB-3 though, not much can touch it for sheer brutality!
They have some decent pedals, but many have drawbacks and aren't the top pick in their respective categories. I see them as mostly mediocre, with a few exceptions that are classics.