I bought the Hug-a-Bub a couple of months ago when my daughter was four months old and she has hardly been out of it since. We both love it! Very comfortable, the design really spreads the weight of the baby making it easy to carry her for hours at a time and she is a big baby weighing nearly 20lbs. She is very snug and content in it.
The only use I have for a push chair now seems to be for carrying the shopping while I carry the baby!
It may seem expensive for a very long piece of jersey material, but it's well worth it. I would say it is the single most useful baby item I have bought.