Character designs: Mostly win. The live action scar shouldn't be as obvious as the animated scar, but it should be noticeable. The henna arrow is a brilliant touch, but I'd like it to be more vibrant.
The casting: is there anything that I can say that hasn't already been said? Well, maybe this: I cannot in good conscience go see this movie. I was excited for it. The fact that the creators of Avatar were vocally in favour of what Shyamalan was doing was a great comfort to me*, and then this happened.
*-- Come to think of it, I haven't heard anything from them recently. In fact, not since before the whole casting debacle came to light. It could just be because I've fallen out of the Avatar fandom, and was barely connected to begin with, but I think I would have heard something if Mike and/or Bryan had spoken publically. That's rather telling.