Having been on the flight I can say with some confidence that as far as I could see all passengers were off within a few minutes.
The criticism I would have is that the FC took too long to decide to return to the stand after the fumes were detected. In the cabin I was in (rear) I would say the evac was handled as well as could be expected in the circumstances.
The major problem was the complete lack of an emergency plan by PHX airport/BA, i.e. why was everybody left on the tarmac for about 20 mins? Why was everybody just led into the terminal building and told to go to the BA desk (shouldn't everyone be put into a central, controlled area, a conference room or similar)?