I asked Rebellion about it when i was on RVG forum :
Myself:
AVP PSP, really put together in under 5 weeks? Or media myth?.
Jason Kingsley
Yup 5 weeks from start to finish with an existing engine in place and lots of retained knowledge. They even managed to make us change the end game boss to avoid film spoilers, then release the film trailer complete with spoilers in it anyway.
So to be far,whilst it is awful...i have it in my PSP collection, there are reasons why it's so awful.