We have a Great Pyrenees. "Bear" is our first one, and our first "outside dog", so it is taking some getting used to.
On the "down side", I guess I found it hard to deal with the typical "puppy behavior" that goes on when you are not there at their side constantly, like you are with your house pets. He dug, and chewed, and dragged things out. I would get after him, but he still enjoyed doing it. It is just harder to teach them right from wrong when you are not with them all the time. But, I guess maybe that is not breed related, but more puppy related. Also, now that he has discovered his voice, he has been barking a lot at night.
On the plus side, he is great with kids, LOVES the horses, loves people, and seems to stick around quite well. He spends most time in the yard and pastures, but he may wander off at night, but I have never actually seen him do so. I have seen him go down the driveway onto the road, and as soon as I see him I call him back and he comes running, so that is good that he listens well that way. I also think they are a very pretty breed.
I also think they are a stubborn, or strong willed dog...easy to disobey you if they think what they are doing is more important.
I was SERIOUSLY second-guessing myself a lot after we got Bear, but after awhile, he has gotten better about the chewing and digging, and afterall, he did already prove himself to us the night he went after the bear in our yard. Since he was only 8 months of age, I was even more impressed, so I guess he's here to stay.