With the exception of my time in the military, I have had dogs all my life. A Golden Retriever, a Doberman Pincher, a Border Collie/Dingo mix, and now, my first small dog, a Yorksire Terrier.

So, obviously, I've gone from working breeds to now having a companion breed. The biggest differences are obviously ease of care for the toy breed. Everything is smaller; food cost, vet bills, messes (she's still a puppy), etc.

The hardest dog to care for was my last one, the collie/dingo mix. He was very aggressive and highly territorial, especially as he got older. The mix made him a large dog for his breed, 55 lbs, and even though I was Alpha, he WAS Beta. No one else could control him.
We finally had to have him put down after he started attacking family members. He was 13 years old and the only dog I've ever gotten from the pound.

While altruistic, getting dogs from the pound can be problematic. They are damaged, otherwise they wouldn't be there. Initial training of a "rescued" animal requires a significantly greater effort then one from a reputable AKC registered breeder. And even then, some hurts are too deep to heal.

Suffice it to say, taking on the responsibly of a dog is only a step or two below the responsibility of a child. It shouldn't be done on a whim and not if you aren't ready to responsibly care for another intelligent living creature for at least the next decade and a half.