I have a one-year-old blue heeler/border collie/husky mix. Exercise and socialization are key for any dog to be well-adjusted. Even though my boy is surprisingly lazy given his breeds, I make a point to take him on long walks or out to my parents' farm where he can run. When he's tired, he is easier to train, less likely to be bored, and more apt to listen. When he is bored, he tends to get destructive, so the key is to have lots of toys he can chew and lots of patience when cleaning up bits of fuzz or plastic from these toys. My dog is also a digger, so we have the additional joy of filling in his holes before someone busts an ankle.
Heeler breeds tend to get very territorial. They make good watch dogs and if trained properly, they should stop barking or approaching your guests at your command, but this will take some effort on your part. Socializing is key here. We began socializing our dog from the very beginning, allowing him to meet cats, puppy-friendly dogs, and small children. The key is starting this early (we began at 8 weeks when we got him) and constant supervision. We made a point of asking other owners if their dogs were good with pups and we would always be around to supervise. We had my little cousins and our friend's little boy come over and play with him regularly. He met our cats immediately, where one established dominance early and the other became his reluctant best friend. Again, we were there to supervise to ensure that the puppy's playfighting and biting weren't hurting the cat. He struggled a bit with meeting large men (barking and running from them), but after some persistence, we were able to overcome this. He loves people and other cats and dogs. The only issues we've had with him are when other dogs bite or lunge for him. Of course, he will defend himself and as he is a mid-large dog, we are very aware of his size and the damage he could cause. We remove him from the situation immediately.
Heelers, being herding breeds, will try to herd other animals and small kids. Googling activities for these purposes will help with this, though I have yet to use any as my dog doesn't seem to have a herding bone in his body.
As for the husky side...well, our dog's main problem with that side of his genetic make-up is the overheating. Having a water bottle and a small collapsible dish is a must on walks. Also, when buying a pet bed or a dog house, don't spring for an insulated one unless you live in a cold winter climate. Our dog spends approx. 15 min a night on his bed and the rest is spent on the tile or laminate floors where it is cooler. He also had a slight pulling problem, which I attributed to the husky side, but it was quickly remedied once we started using a harness for his walks.
Health wise, he is in great shape and we have yet to come across any major issues there. Again, we make sure he gets constant exercise. Our vet's only concern for the future is his overbite (not really sure where he got that from), which causes a couple of his teeth to rub together. We just monitor him regularly.
He is a great dog and I love him to pieces, but we've put a lot of work into ensuring that we've addressed any behavioral issues that can arise due to his genetic make-up. We have friends with blue and red heelers that did not address some of their issues and as a result, one is super territorial and the other is super jealous and aggressive to other animals. Definitely do the research and be committed to putting the time and effort into exercising and socializing them. The payout is amazing if you're willing to do it.