I'm not sure why, but I've never trusted male contraceptives - other than a vasectomy (condom too, I suppose). I trust that the female pill works because it has been perfected over decades. A 'male pill' or anything short of a vasectomy wouldn't have a lot of history to go along with it, to show that it has a high success rate.
Also, I think that the female pill's simplicity is what makes me trust it. It seems that it's easy to trick that female body into thinking that it's already pregnant and therefore not to release an egg. You can't really trick the male body into not producing sperm.
Now before anyone starts, I am aware of the risks associated with the pill - I know it's not 100% either.
I just trust it more because there's more history of it working than there is with new male contraceptives.
As for this specific form of male contraceptive, I return to my previous comments. For me, I would like to see success/failure rates before I jumped on board as a supporter.
-Tamerlain