First time Rottweiler owner? Join the club.
I don't believe that having had a Rottweiler in the past makes you qualified. It's whether or not your lifestyle matches the needs of the breed, and whether or not your have the willingness and the resources to dedicate to a dog (any dog, for that matter) is what makes you a good owner.
Read and research. Don't downplay the facts: you must have time and be in a stable financial situation in order to own a dog, especially a large working breed dog.
If you are getting a puppy - be ready for many sleepless nights. You must take out your pup every 3-4 hours for the first month or so - not to put the strain on the small bladder, and to develop good potty habits. This includes those hours at night that you are probably used to dedicate to sleeping. Weekend mornings? Gone. You'll be up bright and early walking your pup.
Rottweilers are a working breed - they must work. Every day. Whether you are sick or healthy, whether you feel like it or not, whether the weather is nice or scolding hot, or freezing cold. You must have a plan for those days when you have a fever, or have a long day at work. It's like having a child - you can't take a break without planning out the important details.
Rottweilers must be kept in formal training for the first 2-3 years of their life, and if at all possible, as long as they are healthy. This is a no small expense. Don't listen to those who say you can train your dog yourself - you absolutely must find reputable trainer and sign up for classes.
And, of course, be ready for fun surprises. Apparently, many Rottweilers like to sleep on their back. They pass gas, that can clear out the room full of people, and I swear, flowers melt on impact. They will create and teach you their own games. They will learn new tricks faster than you will be able to learn how to teach them new tricks.
The moral of the story is - there is nothing wrong with having a Rottweiler as your first dog, as long as you do your research and realize the commitment you must make in order to invite this wonderful, smart, working breed into your life.