While staying on my graphic novel kick, I have read Xoc (pronounced "Shock"). It has minimal text, which I can't complain about since I don't like to read all that much anyway (shock and horror!). The artwork is simply amazing. The perspectives are great. The coloring is great. Great, great, great. You follow a shark and a turtle on their journey to birth their children. It's a little environmentally preachy but I didn't mind that so much. The sea creatures talk, but it's minimal. This isn't a warm and fuzzy book but you do end up caring about the characters and that's what makes the book work. It's definitely sad so I"d put this in the teen category... or 5th and 6th grade if they can handle the depressing. I was a kid who didn't mind that sort of thing so I could probably read this in the 4th grade. It all depends on the kid. You can learn a lot and there are a lot of jumping off points in this book - learning more about sharks, turtles, pollution, illegal fishing, etc.
(it has bloody scenes so it's not for the squeamish)