PDFs showing series 5 Mixels and the Max model for each tribe have been found at LEGO.com by Ice Ender. I believe they are the first official images of them to emerge. I would link to the source but he didn't tell me where he found them.
They are due for release in June which means we'll probably start seeing them in shops in May.
What do you think of them? Still exciting, or losing some of their appeal?