I grew up with animals. My dad is a veterinarian, specializing in large breed dogs. So we always had at least 5 dogs around the house. Both our own dogs and fosters through rescue organizations. Truth be told, I can't imagine NOT having a dog.
As for what you get out of it, well, here's the truth: you will get out of your dog as much as you put into him/her. Most dogs are happy, and want to please ... but they also need that alpha to lead them. If you can't be alpha, they WILL. And that's when behavioural problems come in.
I have a GSD (German Shepherd) and, I have to say, I love spending time with him more than some of my friends. He's got a sense of humor, he smiles, he's got tons of energy, tons of character, drive, etc. It's like having a best friend. For him, the sun sets and rises with me. There is nothing that dog wouldn't do for me. (It's actually really great for my self-esteem.)

But, I put A LOT of training, time, energy, and money into him. So, our relationship is the way it is because of the work I've put into it. Not everyone enjoys the work which comes with establishing such a relationship. Some parts are easy to work on, and some parts are really difficult. I happen to love dogs, and love the process of establishing communication with them, of training them, etc. It's not for everyone (which is why so many dogs end up in shelters).
And, of course, depending on what type of dog you get, the work level will vary. You don't have to put as much work into a pug as you would a GSD. If you're ready to put the work and time into it, you'll get a lot of love, happinness, fun, wonder, excitement, etc. out of it. If you don't put any work into it, all you will get is a lot of frustration, anger, unhappinness, etc. A lot of it is up to you really. That and making sure to match up the right dog to your lifestyle, i.e. don't get a GSD if you are a couch potato.
