Rottweilers can make excellent companion dogs if they are properly bred, socialized, trained and confined. They are very good house dogs, and friendly in friendly situations if properly socialized as puppies.
Breeders should be doing screening of hips, elbows, eyes, and hearts before breeding, and many people also screen thyroid function and patellas. RUN from any breeder who tells you their lines don't have these issues. THEY ALL DO. Good breeders will offer you the PROOF of the health testing they have done on their dogs, and also the findings on ancestors in the pedigree.
Rottweilers generally live to ages 10, and sometimes 12 years old. Some die younger. Cancer is a fairly big issue in this breed, with a significant incidence of Osteo Sarcoma (bone cancer) and Lymphoma.
Rottweilers are inherently territorial dogs, and for this reason, good fencing and intensive early training and socialization are NOT OPTIONAL. It is the rare Rottweiler that will welcome those who do not live in the home if you are away, no matter how well they know them. Escape proof fencing and locked gates are MANDATORY for the safety not only of people passing by or visiting if you are not at home, but for the safety of the dog as well.
DO NOT get a Rottweiler if you are not prepared for this territorial guardy behavior. It is a hallmark of this breed. Rottweilers need intensive early training and socialization. Have you noticed that I've mentioned this several times? [

] If you are not into dog training, or you want an outdoor dog, please don't get a Rottweiler. These dogs LIVE to be at your feet and with you, and they are miserable when they can't be. DO NOT get a Rottweiler if you don't approve of crate training. They will dismantle your home if you do not judiciously use crates and good confinement.
Rottweilers in a nutshell are LOYAL, loving, confident, outgoing, bold, territorial, defensive, COURAGEOUS, sometimes stubborn, extremely intelligent dogs.
The last thing I shall mention is boy do these dogs shed. I mean a lot. Year round. DO NOT GET A ROTTWEILER IF DOG HAIR BOTHERS YOU. You will be investing in an expensive vacuum too.
If you have any other questions, or if you would like some recomendations of good people in your area to look at for your puppy, please let me know, I will be happy to help in any way I can.