Well, it depends. We have wall-mounted split units in our bedrooms but found the mobile one useful in the lounge, or it could be lugged upstairs to chill guest bedrooms at a pinch. I find that once it goes over 26º-ish in the house it gets quite uncomfortable and an additional chiller can make life much nicer. We do everything possible to keep the place cool in the summer - persianas down once the sun approaches them, windows thrown open when the temperature outside is lower than in, etc., but all it takes is for some idiot to leave the door open (visitors!) and you've gained a few degrees that will stay there unless action is taken!