Andy's acting
I didn't really see his stuff before B99 (other than the viral shorts), but I have to say, I've become a huge fan of his work on the show, and it made me go back and look at a few of the things he's done. I think he's really come a long way esp with his character on B99. He's also pretty funny. It's not the brand of comedy for everyone, but ...
I think getting the chance to work on a more subtle/heartfelt character for months now has really allowed him to hone his skills in the dramatic department and learn how to be funny without relying on as much physicality as he's used to doing (I still don't understand how he gets his face to do some of the things it does). I think he's always had the ability - I got this impression from seeing a video the lonely island guys did way back when - but never bothered to do much with it because he's more into over-the-top goofiness.
Anyway, I think if he wins an Emmy for B99 (let's face it, he's a shoe-in for a nom despite what the haters might say), he'd deserve it. I'd love to see him in more (and hopefully better)movies, like Celeste and Jesse Forever, and going off his older interviews, I think he wanted to be a movie actor as well but sometimes some things aren't for everyone you know? Tina Fey is great, and everyone knows it, but has she ever pulled in huge box office numbers?
tl:dr He's a better actor these days than people give him credit for.