I own a 4yr old Bullmastiff bitch. I've only had her about 4 months but she is an absolute sweetie. She is small even for a bitch, 23ins and about 37kg, and she does have her faults although she is KC reg...I think she's gorgeous anyway! I'll post pics with a friend's Boxer pup for comparison [although he is only 9 months, he's a big boy]
Temperament wise, she is lovely. Great with people, I highly doubt she would do what she was bred for in terms of intruders, but she will bark at strange noises outside etc. She is still building her confidence outside, as she can get slightly jumpy but I don't think this is particularly usual for the breed. She is very lazy, and likes spending most of her time cuddled up on the sofa. She is an intelligent dog and has picked up new commands and training quickly, but can be stubborn when she doesn't want to do something or doesn't think it's worth her while!
She is great with other dogs, usually very submissive, but the most I've seen her do is give a warning growl to the aforementioned Boxer pup when he was...well...doing what Boxers do and getting a bit much for her!
Drool-wise, I don't think she's *that* bad but then I am used to it I suppose! She drools a lot when people are eating, or sometimes when she's playing or in the car...and she's messy as hell having a drink, but just keep a drool cloth handy when people are visiting! Oh, and I have leather sofas as well, they would get soooo dirty if they were fabric...but of course not everyone lets their dogs [especially big ones] on sofas!
Anyway, some pictures:
[still in the collar she came with, can't WAIT til her new one from Paco Collars arrives!]
Really need to get some more, but my camera is playing up.