A lot has been said already, but I'll chime in---
* Keep in mind that I live in a large city, so socialization and how my Dogue relates to people may be a bit different*
First be prepared to draw a LOT of attention with the DDB-- people cannot resist this red wrinkly pup, and if you live near neighbors, you will barely be able to walk around the block without people stopping and wanting to cuddle! Because of so much attention as a pup-- as well as due to probably his temperament-- Mateo has been very social with people---he loves them, esp. kids. Even now, @ 19 months and 131 pounds, he gets a lot of attention in this city (which is a bit dog crazy), and barely a day goes by without someone asking to take a photo of him (esp. tourists).
(I am thinking that he must think his other name is "face", because whenever he hears someone say, "Ohhhh, look at that FACE!" he turns around expecting to be petted, LOL.)
They are stubborn, no way around it. But they do, really want to please you; you are their world. Training should be firm, but no shouting or sharp corrections; they will shut down...it will not work. Firm and consistent (and positive) training works best!
My Dogue is instinctively protective. Just recently when I was sliding down a large rock, Mateo ran up to me and placed his body in front of mne to stop me (even though I was okay-- it must have looked dangerous to him.) Also, he does this thing where if i am sick and curled up he will climb up over me and lay on top of me...like a protective blanket. I will be in the same position if I feel well, but he doesn't do this; it's like he KNOWS when I am not well--- he's done this 3 times already, kind of amazing.
My Dogue is quiet. I think I've heard him bark maybe 4 or 5 times since I've had him. Personally, I appreciate this; except for the snoring, he's as quiet as a mouse, LOL.
He gets along with other dogs- esp. females, but also some males. Except other intact males. He will not start fights, but will also not back down, so this is something we just have to manage--- not a big deal.
He is not food crazy- never eats food off the street, or begs for food. Just not interested...
He loves physical attention...he needs a hug before and after he eats, for example; he will wait looking at his food, and looks to me for a hug. He just wants to be close, physically....a sweet part of who he is. Probably most DDBs are like this also...
He does have a strong prey drive, and will focus on squirrels, esp. very intensely...and will chase them.
How people describe him: that he walks like a lion, and has almost a "human" face.
DDBs are STRONG. Mateo has short, powerful bursts of energy...but not a lot of stamina. Watch out, though, if you are in the path of a running, Bordeaux--- they're like a freight train!
I could go on and on....but that's off the top of my head right now.
Let us know if you decide to bring a Dogue into your home- we'll want pictures!