I lost my last Newfie in July. She was 8 :( There will be more in the future but the time is not right for us to have another dog just now.
Wonderful breed. Very people orientated and usually biddable so long as you put the training legwork in from an early age as by the time the teenage behaviour sets in, they weigh the same as a small adult and are almost impossible to physically control.
Many people have an image of them as big, lazy couch potatoes. It's a misconception. They are working dogs with amazing stamina and will keep going til they drop. They need restricted exercise while young to avoid joint damage but once grown, a fit and healthy one will be able to handle lots of exercise. Although they tend to adapt to as little or as much exercise as suits you.
They need company. Preferably human. They do not tend to do well if left alone for long periods. A bored/lonely/unhappy dog of that size will make its feelings known in ways that will cost you serious time and money to rectify.
They like water. Any water. Puddle or ocean, it doesn't matter to them. They spend as much time as possible wet. Consequently, so do you. And your house. And your car.
They drool. Some more than others but they all drool. Drool is like no substance on earth. If you don't get if wiped off before it dries, you're pretty much living with it until you redecorate. They like to share the drool and can fling it a long way. Look at the ceiling in any Newfie owner's house for proof of just how far.
The hair. My god, the hair. It really does get everywhere and you quickly get used to picking it out of your food. The good news is that they only shed twice a year - January to June and then July to December. They need a lot of grooming. A LOT. Coat maintenance is the biggest downside for me as its so time consuming but absolutely necessary.
And then there's the health problems. Joint problems are always an issue with any giant breed and heart problems are an issue. Unless you're going down the rescue route, it is imperative that you go to a good breeder who does all the necessary health testing and adheres to the breed club code of ethics re breeding.
Happy to answer any specific questions you might have. I'm going offline now for a few days but will be back after the weekend.