I am a strong believer in dogs being a product of their environment. That is why you see one dog that is friendly and another from the same litter that is mean.....
Many reputable breeders will strive for good temperment. Berners are a very friendly and gentle breed. No berner should be shy/fearful and least of all aggressive. Any good breeder will tell you this and stress it. Any large breed dog needs a lot of consistent training. As they get older, they will test their dominance and if a leader has not already been established, then they will take that position. Not to say that we have been strict with our boy Toa, but we have been very consistent and he is 6 months old now and we haven't had any bad behaviour being repeated twice.
I'm also a big believer in crate training. That crate is Toa's den. His safe place. He sleeps there and is there while we are at work. That way he doesn't get into any bad habits while we aren't there, because then we can't correct him and he is the one getting the rule of the house. We decide that he comes out of the crate to eat, pee, exercise, play, etc. From that comes respect, and obedience. It's this way with any breed though....
What I kept in my mind since he was very small was "this is cute now, but when he's 100lbs do I still want him acting like that" . More often than not the answer was NO.
As for them being high maintenance and expensive..... we actually took our pup off of one of the highest rated dog foods (and expensive) because it was simply too rich for him. He is now on something still good quality but much cheaper and is still very very healthy. You do have to brush them often, so there isn't fur everywhere.... especially when they change into their adult coat. We brush Toa at least once a week, and the cats too. But we'd do that anyways because pet hair is gross lol.
In my berner experience, and with all the other berners I know from reputable breeders, these guys are just big goof balls, they are happy and funny and eager to please. They are great with children and other pets (we have two cats and they are like Toa's babies) they love to work and to be around their families and be included in daily household events. Berners are definitely one of my favourite breeds.
My advice would be to do lots of research. Even call up a few registered breeders and chat with them. Many of them should be open to meeting with you and talking to you about the breed. They should never be pushy or try to sell them to you right away. Any breed has its pros and cons, and a good breeder will want to make sure that this breed is right for you.
Kinda felt I had to redeem the breed after you, Bernertalk08. LOL j/k totally. We all love our dogs on here. It's important to consider all of the aspects of a breed and it's good that everyone can come on here and share their experiences
I would recommend a berner to pretty much anyone based on the experience with our Toa.