It's very subjective. My wife kinda hates it. She's a good looking woman, but she certainly doesn't look like she's 20. She often doesn't carry a wallet - so if she's ID'd it can actually be annoying.
I teach an underwater photography class at a university. We were going to have a night dive one evening and a thunderstorm rolled in and we had to cancel, so we decided to go to a local pub that has great food.
There's a bouncer at the door, and he's checking all my student's IDs super close. He's bending them, shining a light through them, etc making absolutely sure nobody underage gets through.
I walk up behind my students with my ID out and he just nods and says "you're good man."
My ID picture is still the same one I took in my early 20s (almost 40 now), and even when I do get carded, 75% of the time they make a comment about how my "picture is really old," "I look really young," etc, etc which is always a punch to the gut.
The first time I've ever been ID'ed was for a beer on a festival when I was 19, we're allowed to buy beer at 16, I was pleasantly surprised.
I've also been smoking since I was 14, which was back then allowed from 16 (now 18), and I've never been ID'ed for buying tobacco or rolling papers.