We have been fostering a Cane Corso for the past month, she is 6-7 months old. We have another dog who is 7 years old. Our experience so far lines up with what I have read about the breed. She is a definite guard dog, if she picks up on ANY anxiety or fear in her owners, she will react by guarding you from whatever is around, whether that be a person or a pet, even if you're anxious about something entirely unrelated. The first time she reacted like that, I was unprepared and it caused a dog fight between her and my dog, the second time she growled at my father-in-law even though she had previously no aggression toward him. However, they are also very trainable, so once I knew, I began to train her to commands - 'leave it'. She now knows that if I give that command all is safe and she drops her guard. I would say DO NOT get this dog if you have anxiety issues or emotional issues though, it will go badly, she will think everything around you is a threat.
If you are a strong, confident person and are willing to put in the time to train them, now she is super sweet to everyone we have over and gets along wonderfully with my dog and the other dogs we have introduced her to. However, she will not back down from a fight, if another dog initiates you will have to step in and separate them, and that is a bit scary as she is huge - so once again you need to be strong and confident to own this breed.
She is super sweet and loves loves loves affection. Gets along great with kids, doesn't like to be left alone but has responded well to crate training although it took time and patience. She has a strong prey drive towards small animals and that will be our next project. Requires lots and lots of socialization with people, places, and other dogs in order to not have nervous aggression. She doesn't bark to warn you she is going to attack or guard, she changes her body language, unlike my other dog who barks and growls, she stands up straighter, puffs out her chest and focuses - snap her out of it then instead of later when she is lunging and you will be much more successful in training.
That's my experience so far... Honestly, I think she would be a great guard dog, and a great family dog, but once again only for someone who is strong and confident and not afraid or intimidated by controlling a big dog. One of the sweetest dogs I've ever met.