Pretty good; I think the hand should be rotated a little more to the right so that it's more obvious he's biting his thumb. I thought he was just holding his chin in thought for a sec. Maybe frankensprite a bit from Lana Skye, or at least check her sprite for reference.
Also, sweat in AA sprites has an outline slightly darker than the skin color, and it's filled in with a white color. Franziska's sweating sprites
are a good reference to use. This is looking to be a pretty good spriteset!
A little off-topic: I don't know how soon I'd be doing it, but would you mind if I tried doing some improvement edits on a few of your sprites (probably some of the Patterson ones)? I've personally been wondering how well I'd do at improving someone else's sprites, so it's more for my own purposes than for anything else. I won't be using the sprites for anything, if that changes anything, it's just a little artistic test for myself. If not, it's all good, just wondering.