Very accurate line work. The shading is spot on and I even enjoy the glimmer of reflection. Props on the background. Though subtle, it adds for a bit of motion... and nothing says "Love" like an attack hug from a PPG.
Now I give 4.5 out of 5 stars because, perhaps I'm a little jaded to seeing some originality to other peoples creations, but these look identical to the characters from their individual shows. Its a beautiful piece; please don't misunderstand my words for any less than a critique.
Great job.