I think they really turned out great, there is some room for improvement though. You are using a relativlely stylized form of drawing, what would help in giving a bit more character is changing up the form a bit. The chins of all of these persons are looking very similar, maybe try some bulkier, thinner, rounder, sharper etc... Apart from that I noticed that the placement of the facial features is a bit off sometimes, I know that these are caricatures, but giving them some level of form will really help making them look more believable. But I am a real fan of the shading, especially on the middle one and the facial expressions all look very sincere and different, a lot of people like myself have the "dead expression" problem, so kudos to you! ^^