If you have a chance to get a newfi and you're ready I'd say you can't really go wrong. I've had Danes, berners, a leonberger (photo) and this is our 10 month old news Koda. He is 130 pounds already, and as big as his 4 year old brother. Things I've learned so far:
1.Super social and great with dogs, kids etc.
2. If you have elderly or otherwise unstable walkers in house, watch out.
3. Eats no more then other dogs, less active.
4. Does not do well when left alone for long periods. As I said he us very social.
5. Get a minivan. Jumping into cars or suvs is not practical and too much on the joints and hips gor these guys.
6. Train him on a leash asap, as they are massive pullers. Get a chest harness leash. Ezydog makes the best one.
7. Heat is a killer for these guys. Have good AC in house and car. They will not survive if left outside in summer. They are indoor dogs.
8. Get pet insurance. I have had good luck with trupanion.
9. They drool when excited, and its some serious drool too.
10. They love to swim, so make sure you can take them to pool, lake, sea etc. They are only truly happy in water.
11. Raised bowls for feeding a must.
12. Prone to gastric torsion so consider stomach stapling when neutering.
13. Wait at least 18 months to fix him/her. Reduces chance of dysplasia.
Thats all I can think of now. You will not be disappointed with this fantastic breed, but it helps to be prepared. Id say the best thing I ever did was get a pacifica van to cart them around in. So easy for them and you. Good luck