Having just gone through the process I found it to be incredibly fair and balanced. There are no secrets to it, do your homework, prepare comprehensively and you'll make it through each stage. BA were nothing but extremely fair, friendly and efficient the whole way through. I've never been through such a well balanced selection, despite working for three previous airlines.
All the information you need to pass is out there. That coupled together with well focused preparation and a good attitude will get you through.
In the last 24 hours I've had two people send me private messages asking me to send them a copy of my application so that they can see what they need to put on their applications and in their essay questions to 'tick the boxes'. Frankly I think that attitude is appalling. I put an awful lot of time and energy into my application, thinking of the qualities I have to offer BA and what they can offer me in return. If you have to ask to copy another persons application then you may as well not bother applying. It's lazy, deceitful and shows no real initiative or drive. There are no shortcuts. If you want it, work for it. Even the much debated computer tests can be prepared for.
Believe me, I know how bitter rejection can taste, I have had my fair share of knock backs. Passing the BA process is very achievable but it takes a lot of hard graft, including focusing on areas that may not initially seem too relevant to our jobs. They set the standard, it's their trainset after all.
Good luck to everyone applying.