When I first saw Cheif Thunderhooves in the show, he was everything I admired in an Indian Cheif: strong, dignified, yet he had heart of gold. You captured these traits perfectly in this piece. The same goes for Little Strongheart, as you captured her fierce determination and her gentle nature all at once. I'll admit, both of them look a little like typical Native Americans that you'd see in any kid show in this, but there's only so much you could do given their designs from the show, so I'll not be harsh on originality. Overall, this is a great rendition from animal to human. You captured these two great characters with all the dignity they deserve. Excellent work!
It's very beautiful artwork! I don't know if I would be the best critiquer, since I am not familiar with what makes art "good" or "bad", but I can offer my opinion. I hope people take an example from you, there isn't nearly enough Strongheart fanart!