I'm not sure if Thor counts as a Teacup anymore because he tipped the scales at 4 lbs and 1 ounce at the vet the other day.

I'm so proud of him. That being said, I have yet to see a yorkie that's smaller than him in my area.
I got to know Thor before I adopted him, so his size was not an issue for me either way. That being said, here are what I see as the benefits of a very small dog:
- Permanent puppy cuteness their entire lives.
- Small poops and pee.
- You can take them anywhere.
- They are very easy to control. I can put Thor on my desk at work, and boom, he's up there until I decide to put him back on the floor.
- Food is cheaper.
- You don't have to worry that your dog could hurt someone.
- You can keep them entertained in small areas. I took Thor to a baseball field tonight and he had the time of his life running back and forth across the diamond.
Here are what I see as the cons:
- Your dog is more vulnerable to other dogs, birds of prey, and being tripped over.
- Greater anethesia risk.
- Your dog may have trouble being a dog. I struggle to find things small enough for Thor to enjoy. Most bones are too big, even flossies. He can't make a normal dog toy squeak. Even in toy dog play groups, he's the runt and gets picked on.
I'm sure I've forgotten some pros and cons, but regardless, I love Thor just the way he is.