They can be quite mouthy/teethy puppies, due to their gundog-retrieve-with-mouth heritage, but you'll be used to the puppy biting after having had high energy breeds in the past.
We had one that barely mouthed/bit at all as a young pup, whilst our most recent is the other extreme and took 'land shark' to a whole new level, but she has some working retriever in her bloodline and is a complete fruitcake anyway.
As a PP said, show line golden retriever pups are usually pretty chilled. We've also found that they are very sensitive to our emotions and really easy to train because their sole aim in life is to please their humans. All our goldies have been very clever, playful, fun to be around and have loved people so much that it's like Christmas each time they see someone they know.
They also love food, adore water to the point that as pups they can endanger themselves in ponds, rivers etc, and all goldies are mud-magnets, though they can be trained out of this. We haven't because of the sheer joy ours get from mud and water on walks and because cleanup at home is fairly easy -- because of their love of all water, lol. Oh and most of them shed a lot of hair, a lot of the time. (Our current one doesn't but I think that's the working part of her.)
I grew up with a border collie, gsds and a doberman at various times, but since getting my first goldie I've never looked back. They just fit in so well and are such happy dogs, whether we're hiking, relaxing, playing or socialising, though they really really hate conflict and can apparently get very depressed in a hostile environment.