As far as I have experienced with my first dog...
They are loving animals, always wanting cuddles and to be loved. This does mean a giant dog will assume it can jump on your lap without you minding, and lick you in the face right after they've licked their butt.
They need regular walking which means you will need to be more active, great! We're all health concious aren't we!? But that does mean in all weathers, so you'll need to enjoy walking in the rain and cold and own a decent pair of wellies.
Speaking of wellies, the dog chewed mine, I refused to buy more, so they have bites out of the top. Also had to throw away 4 dining room chairs, 3 solar lights, numerous children's toys, etc (endless list) oh and explain to the children where their haribo that Father Christmas gave them went. I could go on....
Our dog has a skin condition so she needs special shampoo and medicine. And her stomach issue means she needs specific food too, and any other food makes her poorly (try picking THOSE poops up!!). Rather expensive!
No one wants to look after her when we go on holiday, so it costs us an extra £200 every holiday. We couldn't fit luggage and a large dog in the car, so we don't have a choice!
The kids love her, one of their best friends, they really love her. No negatives here.
Oh I vacuum twice a day as she sheds like mad!
But seriously, if you're thinking of getting a dog. Think about the cost. Not just the initial puppy cost, but also the insurance, the food, the toys, the beds (she's had 4 in 2 years), the things they destroy, the training classes, the extra time you need to walk them and clean up after them. If you're okay with all of that, then you'll absolutely adore having a dog in your life :)