There are many different things to consider when looking at the possibility of a quality portable air conditioning unit. There are many pages and reviews online, but in a nut shell what these are all about is that they are small portable AC units which will cool down an apartment, and only require a small hose for venting out almost any type of a window, making them very handy for many places. One of the better reviews I've seen that go beyond sales pitching to actually doing comparisons and giving quality information is this Everstar portable air conditioner review. It goes over pros and cons, addresses bad press, and talks about whether or not they are a good deal, giving both sides of the story.
This is a picture example from Amazon of what these might look like: