Pretty rapid decompression but once it’s equalized there is no problem walking near it. Would be windy, loud and stuff blowing around - just keep the O2 mask on.
The venturi effect of air rushing past that small opening at 400mph would definitely create a continuous suction. How much? Certainly enough to suck a piece of paper out the window, but would it be enough to continue sucking a person out? I don’t know.