I haven't had kanagroo jerky, but I have had roo as a sandwich and it was very good, if a little tough. I would imagine that the quality of the jerky was more to do with how it was seasoned and dried, rather than the meat itself. I have had a go at making biltong a few times and bought pieces from four or five other places and even the beaf stuff has varied hugely depending on how it has been prepared.
What made your jerky so bad?