My experience with LanChile last was:

They cancelled a flight at two weeks notice and refused to fly me to the only adjacent airport which had a flight on the day I required. They took the attitude that I had a ticket issued by AA so I was their problem. I had book CCS-SCL, but had to pay to fly CCS-BOG, where I picked up BOG-SCL on LanChile. They issued this segment seperately and took the coupon out of my book.

However I would not think that LanChile are typical of oneworld.