What if....
 

I sat watching the film Aliens last night and it made me wonder. At the end of the film the character Ripley opens the hatch to the bay where you would exit to outer space. This being a chamber type set up, an inner door and an outer door. As the outer door to space is opened the alien hangs of her foot, she has her arm hooked round the steps in the chamber and with both doors open, manages to pull herself back in to the ship to shut the doors once the alien has been blown into space.
My question is, in the event of both doors being open in space, how severe would the explosive decompression be? And how long would it take to reduce the interior of the ship to the same vacuum level of space? Would such an explosive decompression damage the structural integrity of the ship?