It is the crews decision to evacuate. Primarily it will be the flight crews decision to evacuate and if clearly catastrophic, the cabin crews. In the event of a clearly catastrophic situation and with no clear commands from the cabin/flight crew then it is the pax who will undoubtedly decide.
As for the window blinds. Many of you forget that pax are charged with opening certain exits and so whilst it isn't their decision to evacuate, it will be them who assess whether it is safe to open and use that window. Hence the window blinds need to be left open.
Leaving the blinds open also helps the fire services to assess conditions inside.
Generally, crew are all trained to the same standards when it comes to emergency scenarios but as with any job, some crew are better than others.
Last edited by easyflyer83; 2nd September 2014 at 18:55.