Take all of the worst aspects of BA rostering and multiply them by a factor of 4. That should give you a rough guide!
I also seem to remember that they can reschedule your holidays and also your operating base at the drop of the management hat.
Don't forget it's a meritocracy so best you get real pally with Dale Moss and his mates.
Yes I do work for BA but I also looked at the OS contract in order to have a balanced view (also in the fear it may be imposed on me in the future). It really doesn't look very good.
Good luck if you go for it though.