Big feature to look for is the ability to run at lower temperatures, unless you keep your basement heated to a fairly high temp. Many units may ice up and freeze at temps below 70 degrees. The good news is that they throw hot air, so it'll warm the room up for you fairly quickly. The bad news is that it does the same thing in the summer time when heat may not be your biggest desire.
Some are pretty noisy too. My big kenmore unit makes a ton of noise and half of it is cheap plastic case buzzing.
Its basically a big inefficient air conditioner which condenses cold water into a bucket and blows its exhaust into the room.
Some portable air conditioners can also function as heaters, air conditioners AND dehumidifiers at the turn of a switch...you might investigate one of those...provide you cooling in the summer, heating in the winter and dehumidification all year round.