Some Staffs do require alot of attention, but it just depends on how you are with em.

Daz lays in his bed most of the day, it's only walk time when all hell breaks out

As for em turning nasty, i know loads of people with kids and staffies and the worst that ever happened is the kids getting knocked over. and if that cheaky chap in your avatar is your son looks like you'd have more trouble with him