As has already been pointed there are rather a lot of potential health issues within the breed and unfortunately a lot of these currently can't be tested for. This means that extreme care needs to be taken when finding a breeder who takes health seriously and is doing absolutely everything they can to ensure the future health of the puppies they breed. Even then, as there aren't tests available for many health conditions it's always something of a lottery.
The minimum tests that should be done are hip scoring, elbow scoring and a BVA eye test plus they should have participated in the breed council health scheme which checks for skin issues, eye conformation (they can be prone to entropion) and general soundness. The breeder should also be well versed in health issues present in the breed and have thoroughly researched the lines they're using for any signs of any of these conditions. The breed is also becoming increasingly brachycephalic (short-nosed) and I wouldn't touch a breeder who isn't purposefully trying to avoid this.
Temperament-wise they're also not for everyone and are relatively specialised dogs. They're traditionally a guardian breed and haven't completely lost those traits, they also tend to be relatively prey driven. Your friend would need to be very confident in their ability to manage both these things effectively. Due to their conformation their body language can be quite hard to read, both for humans and other dogs.
They need plenty of socialisation as puppies and even when well socialised they're generally not the type of dog who backs down from a confrontation.
Obviously they're very heavily coated so do require a fair amount of grooming to prevent the coat becoming tangled or matted.
They don't need masses of exercise but providing what they need can be tricky as they're not always brilliant off lead and you need to be very careful in summer that they don't overheat.
In short, they're pretty specialised, it's difficult to find decent breeders and they're not dogs for inexperienced owners.
If she's still keen on the breed I would recommend they go along to shows and talk to as many owners and breeders as possible, as well as meeting lots of examples of the breed.