They are friendlier and less reclusive than some species. The advantage for pet owners is that they are diurnal (day active) so they're out and around when you are. They tend not to try to escape and don't bite much compared to some species. (for instance O. vulgaris tries to escape a lot, and many people have been bitten by O. rubescens- not too bad a bite, but still a bite)
It's difficult to distinguish whether a bimac is male or female - in some species, the third arm of the male is longer and a bit different, so it's not so difficult.