Ditto Barabara only thing I would ad to the Boxers are bouncy and often clumsy pups AND they are pups till about 2 1/2 years old Make that around 7ish LOL!!! my boy is just calming down, and my girl who is 5, meets herself coming the other way.
Please , Please, make sure this is the breed for you, to many people see a Boxer puppy and fall in love, (who can blame them) but they can be hard work, some more than others some lines are far more Hyper than others..
Boxers are no harder to train than any other breed, you get out what you put in....they do suffer from selective deafness, some are more stubborn than others, usually the males, my lad lives his life on a whats in it for me basis.
Just a little tip, get your puppy off lead (in a safe environment) as soon as possible, the sooner you teach a good recall with a Boxer the better (as with all breeds)
Do your Boxer a favour, turn him into a well behaved canine, as others have already said, a out of control Boxer is a nuisance, and you will make many enemies , dont use the excuse , he is a Boxer, and thats the way the play.
Good luck and enjoy!!!