i can tell you what i know of bully breeds in general, keep in mind the majority of my experience with the bullies is with staffies, but ive met a few bull terriers...
they are in absolutly NO way shape or form STUPID...there silly yes but NOT stupid (ANY dog repeatedly walking into any object should be checked for mental problems repetative strange behaviours like that are usually a sighn of a nerlogical problem or boredom! eitherway that female shouldnt be bred untill its figured out!)
there the clowns of the dog world...most people think clowns are stupid when infact there the most advanced performers of any circus often doing things that the other acts WONT do as well as all the tings they CAN do...so think of the bullies as the clowns. constantly doing things that seem "silly" to amuse you.
they can be very stuborn and need a firm but kind hand to train and constantly need "refreshing", the nothing in life is free method of training is GREAT for ANY bully breed. and watch for dominance issues. early socilization with people and other dogs is a MUST!
MOST bullies are wonderful with kids (im not familiar at all with amstaffs and pretty unfamiliar with pitties, but all the bullies of other breeds ive met are great with kids)
ive had the priledge of knowing 3 bull terriers very well andmeeting about 300 total...and none of those dogs were "stupid" they were sweet and very silly dogs, always making their people laugh...one owner even told me, of all the breeds hes never had one who tries so hard to make him laugh as his bullterrier...but saying bulls are stupid is ridiculous, ive never known a stupid dog to learnt to open cupborads and the fridge to help themselves to snaks, this one could do more tricks than a performing monkey, was sweet and frinedly even with dogs and its own pet rat (who traveled round all the time with the bull terrier riding on its back or in a backpack for dogs) he aparently taught himself most of the tricks he performed, was atherapy dog in a childrens hospital and could open the sliding glass window, get in draws and put his own sweater on. on that doggy inteligent test you can find around, this bull terrier schored in top ranks, had his canine good citizen award and was a seizure alert dog for his masters wife (seizure alret dogs cannot be trained to alert!)
in NO way was he STUPID! he was a silly one though often rolling over with his tonge out lolling to one side for belly rubs, or tugging you pant leg when you wernt paying attention, and seeing him pick up his ball take it to the top of the stairs and roll it down when noone woudl play fetch with him.
i take pride in the fact ive met MANY stupid people but not one STUPID dog...and the bully breeds eyes scream inteligence and kindness...
ignor the first comment, seems like they were trying to start issues....
there are pros and cons to this breed:
they are loving and fun loving
good with kids
usually good dogs
beautifull
inteligent
can be stubborn and difficult to train in the beginning (refresher courses a must)
some have dominance and dog agression issues (socilize socilize socilize)
watch for back yard breeders...ive seen a few backyard bred bulls with advanced neurological problems often in the forms of repetative behaviours like walking into walls, agression to paws and tail, or circle walking...ect) a good breeder is an absolute MUST with a breed lik this to ensure sound body temperment AND mind.
and avoid poeple llike the first comment maker up there...lol.
hope this helps.
my biggest peice of advice would be to contact breeders, attend meets go to shows and see them in action.