Gin: How do I say this? Umm... He looks a little... compressed if you know what I mean, his face looks more like Vodka's... His eye is too big,but his clothing is really good.
Haibara: The right side of her face is pressed in, and her hair looks too 'solid' if you know what I mean. Also, her body's smaller than it should be, and she's lacking eyebrows.
Kaitou Kid: Somehow, he just looks 'off' to me. I can tell it's my Kai-chan, but I think his nose is too high up and you need to move the eyes down and add eyebrows. Also, the string off his monocle is thinner.
Kogoro: This one resembles the character most, but his hair looks kind of weird... I think his eyebrows are thicker as well...
Keep in mind that I am not trying to flame you, and that these are actually pretty good. I just think (like everything in this entire world) it could use improvement. Hope these tips helped you!