This is a bit more than just new art... the expressions are very different. The big critique I have for the new one is that there isn't a homogeneous scene, as every character is posing with different intents, which looks very artificial (especially Ears, the only one staring at me). The old one was more unified. And Vorpal looked both creepy and crazy in the old one, while now he is far more relaxed (although the character has changed a lot, so it could be a reflection of how he is now). There's something odd in the field they're standing in, too, and I have problems placing the new ones in space.

The huge steps forward I see concern the bulbous eyebrows, which look far more 3d now, and the ears, which now have actual readable shapes. In general, the modern faces are hugely better, although I agree that they look a few years younger. The necks are more structured, and the characters have a few different kinds of torso.