We have used one of these and really liked it, but I must admit that I REALLY loved our ERGO even better. If you only had so many dollars to spend on one, I would spend a little more and get the ERGO. We went through and grew out of our Hip Hammock, but FWIW I can still use our ERGO with our almost 4 year olds if necessary. It does take a little bit of practice to be able to use them by yourself, but it is very doable!
BTW, if you do choose to go with the Hip Hammock, if you can't get it positioned correctly it will start to weigh on your neck and shoulder. I have heard that if you tighten it more it will get more comfortable. I think that the logical thing is to loosen it, but it does better if it's tighter.
Good luck with your choice!