I've got two maltese furbabies - littermates - and they are awesome, loyal companions.
They've got different personalities that continue to develop as they get older. They are truly "people" dogs - they'd rather be inside with their humans absorbing the conversation than running around a yard. They think everyone who comes to the apartment is there to see them. They are extremely intelligent and eager to please and pick up commands like lightning when we're training with the clicker. (Although the little boy gets an attitude when we repeat the same thing too often; he obeys but is such a drama queen about it!) Mine aren't aggressive in any sense, they mind well, and are excellent watchdogs. (A little too excellent - I've got an ultrasonic bark-breaker that keeps them quiet when they're inclined to take their job too seriously.) My little girl loves training and has a little "happy dance" she only does when we've had a training session.
As for stamina - many maltese are in agility and can likely be trained to hike longer periods than inside dogs - though I'm pretty sure they'll never give a malamute a run for its money. There are backpacks and jogging stollers available to carry them if necessary. (I suppose those are good for older, arthritic dogs who can't get around outside as well.) One consideration is that maltese don't have an undercoat; their coat is like the hair on our heads, so they legitimately need sweaters/coats (and possibly boots) in cold weather.
Being so little, I can sequester them in the kitchen without feeling they're cramped and I don't need large, heavy, expensive gates to block passageways. Mine are litter-box trained - an advantage of having small dogs. No walks in the rain or snow for us!
Being so small, they also have a longer anticipated lifespan: 18-20 years. I'm hooked and will likely stick with the breed when my two pass on.