Can I use a portable air conditioner instead of a split-type unit?

Mobile air conditioners need an exhaust hose that leads outside - that's the big difference from split units and what makes them less efficient, because warm air is constantly escaping and new air is coming in. They work, but they're louder, more expensive to run, and don't cool a room as reliably as a split system. If you need flexibility and can't or aren't allowed to drill, mobile units are fine - otherwise a split unit is definitely worth it in the long run.