Audio quality is very good considering the price. Good bass, sharp and clear audio. Vocals seem a bit harsh sometimes, but using an equalizer easily fixes that.
The build quality: The airdots themselves are well built; rigid, no moving parts. The case though, feels very cheap. The lid is very easily breakable. Everything is plastic, no metal anywhere. It's very slippery, and easy to lose.
Comfort: The hard plastic can feel a bit uncomfortable, but you'll get used to it. They fit snugly, and don't fall out no matter how much you shake your head. They're very light, and you'll forget that you're even wearing them.
Controls: The controls are a big let down. You can only pause/play music and 'summon' the voice assistant. No volume controls whatsoever, and you can't change tracks either. The controls is a button on each earbud. Pressing the button pushes the earbud around in your ear, and is a very uncomfortable experience.
The bluetooth connection seems stable. I've had some trouble with some devices, but it works fine on my android phone.
Overall, it's a very good product, but the controls are abysmal.