Picture a kid, who doesnt need sleep, have uncontestet lunacy and have a mouthful of razorsharp teeth, then you get a pretty good idea on how Una is.
She also have quite the homicidal streak, and usually uses her incredible stupidity to lull the opponent into a false sense of security. Then she scores a Td.

All that being said, Una is a Critter you cant get around. She´ll kill you if you try.