I've had Maine Coons (MCs) for about 20 years now...Currently have 2 as one PTS 2 years ago. I adore them but they are all very different in personality, like all cats (I had moggies before) and I'm not sure that they really are any more unique than any other baffling and engaging moggie. Its just like all besotted cat owners, we are convinced (brainwashed?) into thinking they are...
Anyway, they are big, heavy cats. Massive paws, tails like feather dusters, faces are so beautiful.... But their fur does differ in texture. Some can't groom to save their lives - and won't let you unless you want to lose a finger either!! One of ours regularly had to be shaved at the vet.
They are VERY VOCAL. If you don't pay attention they will assault you from behind around your lower limbs. If you don't want to get up to attend to them in the middle of the night, they will jump onto the bed via your chest. You get my drift... They are very people orientated cats and do fixate on one person in families.
Health wise we have had a few problems They can get hip dysplasia (more common in dogs) simply due to their size. Check with breeder. One of ours did but he was never any the worse for it. Another however suffers terribly from urinary tract infections - vet not sure if this is connected to size (he's the enormous one!).
Unlike most pedigree owners, I had a strict policy of letting mine outdoors as I think cats ought to have outdoors access. Ours have never come to any harm.
Ours have tolerated children and the introduction of basset hounds (?!)..
Can't recommend them highly enough. One of ours is 17 and I am looking already into getting another from Maine Coon Rescue if she sadly goes.