are they prone to health problems?
are they hard to train?
Do they get along well with ohwer dogs?

Thanks

Healthy problems. Prone to same conditions as all giant breeds ie hip displasia and OCD. Buy from hip scored parents ( breed average 26 I think)
Heart problems. Buy only from parents who have been echo dopplar heart tested
Training. They are willing to please and can be trained pretty well but probably not the sharpest tools in the box! You will have trouble getting them to get out of water!!
Other dogs. As a rule friendly and kind natures with people and other dogs but need like all dogs good early socialisation.
Amos 

Also take into account the mess they make of your house.  They need constant grooming and when the mud dries in their fur it then magically transforms into dust and in one day makes your house look like it has been left uncleaned for years!  Also some people even newfy owners will tell you they are couch potatoes.  Some are, but most aren't.  My bitch has easily more energy than my English Springer!  And as the others have said make sure you only buy from breeders that have the health checks in writing.