It does it’s job but it’s suuper ineffective - you have to have a window open to suck in (hot outside) air that the portable AC cools itself with and throws out.
That open window even with that “sock” cover it comes with, lets back so much of the outside air and if you are like me renting a badly insulated flat, you are comfortable only when the AC is running, it won’t really cool down (and keep cool) the living space.
I do wonder why they don’t make a dual hose portable systems so that at least the unit is not pulling the air directly from the window, mixing already cool inside air with the hotter outside one.