We have a secondhand Possum one I think - it's basic but really comfy for both me and DS. Didn't start using it until he was 6 months old, but only because that is when we bought it. Has a nice wide waistband and feels just as comfortable as my Macpac travel/tramping pack (which is probably of similar age).
These backpacks are great to use when travelling by plane etc on your own - you can fit sooo much baby gear in the pack themselves and its great having both hands free for your own luggage. Plus makes the trek through the airport with bubs much easier.