
I've known a couple very well though never owned one (I do own a similarly heavy long coated breed though).
I cannot emphasise enough the need to get a pup used to being stood on a grooming table, brushed, combed, showered, dried etc from day 1. It is likely to be a two person job to start with, one feeding treats in one end whilst you brush the other end, and expect to spend a small fortune on grooming equipment and shampoo and conditioner!
I honestly would NOT suggest anyone get a breed like this if they are not prepared to do much of the grooming themselves, even if after six months or a year you decide you willa ctually take him to a groomers to do the really big jobs, the benefits of having done all that groundwork yourself will make a huge huge difference.
It is extremely hard work if you have a dog you haven't really the facitilities to groom yourself AND hes muckied his copybook with every groomer in the district (as my friend with a St Bernard found out, though not her fault, he was aggressive and hated being groomed way before she got him!).
Personality/behaviour wise - these are a big dog, the coat is big but believe me, the dog under it is a solid chap too. Lots of socialisation and although I'd say this with any dog, never EVER teach a dog like this not to growl, because particularly when they are full coated, their facial language is incredibly hard to read and if they have had their growl removed by punishment training, they really CAN 'turn without warning' (in inverted commas because obviously its THERE you just can't see it so well).
They are clowns and they are funny with little foibles of their own. They like to herd and keep everyone in a group so do beware of this when out and about as they can decide that a group of peopel MUST stay together... even if they actually are all strangers! More usually they will try and keep the family together and won't like it if you split up and wander off!
Brought well they are a lovely dog and I would love to have one one day, but if not given enough to do they WILL figure out their own games and that can easily turn into learning that barking is FUN - with sufficient mental and physical stimulation that won't happen but if you slip there and accidentally they hit on shouting as a way to get attention, believe meits a BIG noise and a pain in the bum to sort out. One of the ones I knew had learned to throw his ball down places hard to reach th en shout at his Mum to get it... and then when she tried hed dash off and get the ball and repeat the process. He would also shout constantly the minute the car turned for the park (and the park ha da LONG access road, you could hear them coming half a mile off he made so much noise!). However to counter that, this was a dog left for long periods on his own and somewhat misunderstood and not given nearly enough things to do!