Pros:
*They are the goofiest, happiest dogs. I find it impossible to not smile when I'm around a boxer (unless Johann has done something on the "cons" list :

).
*Smart
*Love to be around people (especially their people)
*They keep you active with their energy
*Good alert system (usually)
*Great at cuddling
*Slobbery boxer kisses
*Pick up new behaviors/tricks very easily (in my experience)
*Usually good with children and other dogs
*Ours can amuse himself with the simpliest things- a newspaper, cardboard box, new toy, etc
*Sweet and loving
*Low maintainence for grooming
Cons:
*You'll always want 1 more boxer than you have

*They drool and fart, but you get used to that quickly
*Prone to heart disease, cancer, and thryoid disease. If you decide to get a puppy, please, please go to subforums on puppies and how to choose a breeder.
*Require quite a bit of exercise and attention
*Can be stubborn
*Bratty adolescent period (9 months to a 18 months for Johann) when you wonder why you ever wanted a boxer
*Can be destructive (we lost a couch, coffee table, window sill, and kitchen cart. All our fault for lack of supervision and exercise....but still, big dogs to bigger damage to furniture)
*Hard to go for a walk anywhere without someone stopping to talk about boxers (OK, that's not really a bad thing :p )
Overall, they are certainly not the breed for everyone...but I cannot imagine having another type of dog. Johann was my husband and I's first dog (I had a GSD growing up, but she was more my dad's dog). It's been an experience, but we wouldn't trade him for anything in the world. He always wants to be with us, and will follow us from room to room. He was a terror as a puppy, but looking back, the majority of that was our fault and iinexperience with puppies.
It seems like the most common behavioral issues (based on the behavior and training forums) are jumping on people and teaching bite inhibition to puppies. It can also be tough to teach them that a polite dog greeting does not involve a right hook to the other dog's face.
They are great dogs and a lot of fun. Are you thinking of getting a puppy or an adult?