I used to own one, I sadly lost her to bloat aged 3 years and it broke me as she was the love of my life, things to be prepared for are - the rate they grow, literally turn your back for 5 minutes and they double in size, the slobber, Beastie (my Bernard) was quite dry mouthed and we got her used to having her chops wiped from early on, but we had slobber on the walls, the ceiling, the sofa, the kitchen cupboards and mainly ourselves, and the hair so much hair.
The puppy chewing, whilst little puppies chew small puppy sized things, Bernards chew big things, mine destroyed a leather jacket, an iron, a hard hat, too many pairs of shoes to mention plus a pair of steel toe capped boots, and so many brooms she loved brooms 🙄
You have to be careful and limit their exercise when young and stairs and not encouraged as they can do serious damage to joints when coming down the stairs, but get insurance Petplan insurance is best as anything veterinary cost a fortune as they are the size of a small horse so need so much more medication/anaesthetic than a regular sized dog.
My girl was amazing, she was so quick to learn, we brought her home at 8 weeks old and she only ever pooped once indoors, we did have a few wees but she caught on so quickly (unlike my Cavalier cross breeds that are stupidly slow at learning, my current girl wasn't housetrained at 7 months old and not from the lack of trying) but she was amazing, also learn to say no to people as the will swamp you wanting to fuss and hug the dog, I used to have to stop children hugging her in the street as she wasn't keen on it and rightly so, but you'll get lots of silly comments, mainly about Beethoven (the films) getting a saddle for the dog, asking where the brandy keg is etc etc etc
Photos, here are a few as I don't have many on the computer.